How to save colors in gridview after postback? asp.net c #

I have a gridview that I change some row colors after using RowDataBound ....

Here is my gridview

<asp:GridView ID="grdvEventosVendedor" runat="server" AllowPaging="True" 
                AutoGenerateColumns="False" CellPadding="4" DatakeyNames="idCita"
                EmptyDataText="No Hay Eventos Para Este Vendedor" ForeColor="#333333" 
                GridLines="None" AllowSorting="True"
                onpageindexchanging="grdvEventosVendedor_PageIndexChanging" 
                onrowcommand="grdvEventosVendedor_RowCommand" 
                onsorting="grdvEventosVendedor_Sorting" CellSpacing="1" 
                onrowdatabound="grdvEventosVendedor_RowDataBound" >
                <AlternatingRowStyle BackColor="White" ForeColor="#284775"/>

                <Columns>
                    <asp:TemplateField HeaderText="" ItemStyle-Width="35px">
                        <ItemTemplate>
                            <asp:ImageButton ID="imgBtnEdicEvento" runat="server" 
                                CommandArgument='<%# Eval("idCita")%>' CommandName="Edicion" 
                                Height="32px" ImageUrl="~/img/pencil_32.png" Width="32px" />
                        </ItemTemplate>
                    </asp:TemplateField>

                    <asp:TemplateField HeaderText="" ItemStyle-Width="35px">
                        <ItemTemplate>
                            <asp:ImageButton ID="imgBtnDelete" runat="server"
                                CommandName="Borrar" 
                                ImageUrl="~/img/1385_Disable_16x16_72.png" 
                                onclientclick="return confirm('¿Desea eliminar el registro?');" 
                                CommandArgument='<%# Eval("idCita")%>' />
                        </ItemTemplate>
                    </asp:TemplateField>

                    <asp:BoundField DataField="Cliente" HeaderText="Cliente" InsertVisible="False" ReadOnly="True" SortExpression="Cliente" ItemStyle-Width="50px" />
                    <asp:BoundField DataField="Empresa" HeaderText="Empresa" InsertVisible="False" ReadOnly="True" SortExpression="Empresa" ItemStyle-Width="50px"/>
                    <asp:BoundField DataField="Telefono" HeaderText="Telefono" InsertVisible="False" ReadOnly="True" SortExpression="Telefono" ItemStyle-Width="50px"/>
                    <asp:BoundField DataField="Nextel" HeaderText="Nextel" InsertVisible="False" ReadOnly="True" SortExpression="Nextel" ItemStyle-Width="50px"/>
                    <asp:BoundField DataField="Tipo" HeaderText="Tipo" InsertVisible="False" ReadOnly="True" SortExpression="Tipo" ItemStyle-Width="50px"/>
                    <asp:BoundField DataField="Descripcion" HeaderText="Descripcion" InsertVisible="False" ReadOnly="True" SortExpression="Descripcion" ItemStyle-Width="150px"/>

                    <asp:TemplateField HeaderText="Fecha" SortExpression="Fecha" ItemStyle-Width="50px">
                        <ItemTemplate>
                            <asp:Label ID="lblFecha" runat="server" Text='<%#Bind("Fecha", "{0:dd/MM/yyyy}")%>'>
                            </asp:Label>
                        </ItemTemplate>

                        <EditItemTemplate>                                        
                            <asp:TextBox ID="tbxFecha"  runat="server" Text='<%#Bind("Fecha","{0:dd/MM/yyyy}") %>' ValidationGroup="gpEdicionAgenda">
                            </asp:TextBox>
                        </EditItemTemplate>
                    </asp:TemplateField>

                    <asp:BoundField DataField="HoraInicio" HeaderText="Hora" InsertVisible="False" ReadOnly="True" SortExpression="HoraInicio" ItemStyle-Width="50px"/>
                    <asp:BoundField DataField="Lugar" HeaderText="Lugar" InsertVisible="False" ReadOnly="True" SortExpression="Lugar" ItemStyle-Width="50px"/>
                    <asp:BoundField DataField="Estado" HeaderText="Estado" InsertVisible="False" ReadOnly="True" SortExpression="Estado" ItemStyle-Width="50px"/>

                    <%--<asp:TemplateField HeaderText="Estado" ItemStyle-Width="50px">
                        <ItemTemplate>
                            <asp:DropDownList ID="dpdListEstado" runat="server" OnSelectedIndexChanged="dpdListEstado_SelectedIndexChanged" AutoPostBack="True" CommandArgument="">
                                <asp:ListItem>Pendiente</asp:ListItem>
                                <asp:ListItem>Atendido</asp:ListItem>
                            </asp:DropDownList>
                        </ItemTemplate>
                    </asp:TemplateField>--%>

                    <asp:TemplateField HeaderText="Atender" ItemStyle-Width="35px">
                        <ItemTemplate>
                            <asp:ImageButton ID="imgBtnAtender" runat="server"
                                CommandArgument='<%# Eval("idCita")%>' CommandName="Atender" 
                                ImageUrl="~/img/activar.png" Width="16px" Height="16px" 
                                onclientclick="return confirm('¿Desea marcar como atendido este registro?');" />
                        </ItemTemplate>
                    </asp:TemplateField>

                    <asp:TemplateField HeaderText="CRM" ItemStyle-Width="35px">
                        <ItemTemplate>
                            <asp:ImageButton ID="imgBtnCRM" runat="server"
                                CommandArgument='<%# Eval("IdCliente")%>' CommandName="CRM" 
                                ImageUrl="~/img/go.gif" Width="16px" Height="16px" />
                        </ItemTemplate>
                    </asp:TemplateField>

                    <asp:TemplateField HeaderText="VM" ItemStyle-Width="35px">
                        <ItemTemplate>
                            <asp:ImageButton ID="imgBtnVerMas" runat="server"
                                CommandArgument='<%# Eval("IdCliente")%>' CommandName="VerMas" 
                                ImageUrl="~/img/search.png" Width="16px" Height="16px" />
                        </ItemTemplate>
                    </asp:TemplateField>
                </Columns>

                <EditRowStyle BackColor="#999999" Font-Size="Small" />
                <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
                <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" Font-Size="Larger" />
                <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
                <RowStyle BackColor="#F7F6F3" ForeColor="#333333" HorizontalAlign="Center" Font-Size="Small" />
                <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
                <SortedAscendingCellStyle BackColor="#E9E7E2" />
                <SortedAscendingHeaderStyle BackColor="#506C8C" />
                <SortedDescendingCellStyle BackColor="#FFFDF8" />
                <SortedDescendingHeaderStyle BackColor="#6F8DAE" />
            </asp:GridView>

in my cs i have ...

    private static string strColorUrgente = "#FF525D";
    private static string strColorEnCurso = "#FFDE00";
    private static string strColorHoy = "#3ECF00";

and here the function rowbounddata p>

protected void grdvEventosVendedor_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowIndex >= 0 && e.Row.Cells[11].Text == "Pendiente")
        {
            string strFecha = (e.Row.FindControl("lblFecha") as Label).Text;
            int intYear = Convert.ToInt32(strFecha.Split('/')[2]);
            int intMonth = Convert.ToInt32(strFecha.Split('/')[1]);
            int intDay = Convert.ToInt32(strFecha.Split('/')[0]);
            DateTime dtmFecha = new DateTime(intYear, intMonth, intDay);

            if (dtmFecha < DateTime.Today)
            {
                e.Row.BackColor = Color.FromName(strColorUrgente);
            }

            else if (dtmFecha == DateTime.Today)
            {
                DateTime dtmHoraInicio = Convert.ToDateTime(e.Row.Cells[9].Text);

                if (dtmHoraInicio > DateTime.Now)
                {
                    e.Row.BackColor = Color.FromName(strColorHoy);
                }

                else
                {
                    e.Row.BackColor = Color.FromName(strColorEnCurso);
                }
            }
        }
    }

Whenever I enter this page or I use a search engine, I update the gridview using a data source, and of course RowDataBound starts up ... and eventually some row colors will change ...

You will notice that in gridview, in the last column there is an imgBtnVerMas button ...

When pressed, it launches the following function

string strMensaje = "";

        try
        {
            //Method that brings back data from a specific client (returns a datatable)
            //intIdCliente was defined in the CommandArgument
            DataTable dtDatosCliente = ConexionBD.GetInstanciaConexionBD().GetClienteEspecifico2(intIdCliente);
            //Assigning to a string a message that needs info from the previous datatable
            strMensaje += "DATOS DEL CLIENTE\\n\\nNombre:\\t" + dtDatosCliente.Rows[0]["Cliente"] + "\\nEmpresa: " + dtDatosCliente.Rows[0]["Empresa"];
        }

        catch
        {
            if (strMensaje == "")
            {
                strMensaje = "Hubo Un Error Al Traer Los Datos Del Cliente";
            }

            else
            {
                strMensaje += "\n\nERROR!!!!!!!";
            }
        }

        ClientScript.RegisterStartupScript(this.GetType(), "Mensaje", "alert('" + strMensaje + "');", true);

Then a message is displayed, however all the row colors disappear ... I was wondering ... how can I keep the gridview row colors even after the postback ...

thank