You can't change the value list itself, but you can use Conditional Formatting to colorize the field.
As brsamuel says, you will have to use Conditional Formatting for the field. If you leave the default text colour of the field as black, you can then add two CF formulas for the other two colours: Self = "Pass" with the text colour set to green; Self = "Fail" with the text colour set to red.
Try this as an auto entry calc in your Question field (be sure Do Not Replace... is unchecked:
Let ( [
red = TextColor ( Question ; RGB ( 255 ; 0 ; 0 ) ) ;
green = TextColor ( Question ; RGB ( 0 ; 225 ; 0 ) ) ] ;
Case ( Question = "Pass" ; green ; Question = "Fail" ; red ; Question ) )
The default is black for "N/A." You can play around with the RGB values to get the colors exactly as you want them.
Many Thanks to all who responded. The simple solutions are always the best.Thanks again.
You could replace the value list with a series of radio buttons. That way, you could have each radio button and/or the text for them a different color.
Here's how: Instead of creating a value list with three values (Pass, Fail, Green), create a single list for each value (List 1=Pass, List 2=Fail, List 3=Question). Then create a radio button for each list and make them the colors that you want to use -- but use three instances of the same field, rather than using a field for each value.
This would also work for checkboxes.