You should not edit the file with /etc/sudoersany kind of script. There is a reason for the team visudo. File editing sudoersshould be rare and well controlled.
If your editor for the command visudois vi, you can run something like this :%s/^# %wheel/%wheel/to uncomment all the lines starting with %wheel.
Or, if you think again that this is necessary:
sudo sed --in-place 's/^#\s*\(%wheel\s\+ALL=(ALL)\s\+NOPASSWD:\s\+ALL\)/\1/' /etc/sudoers
--in-place, . .