An easy way is to:
Take a print of the color you want to edit, then open it on photoshop or similar.
Use sample tool (eyedropper symbol) to find the color code.
Then search inside colors.xml for that color code...If only one is found - edit it. If more you need to look at the item name and assume what's what, or go by trial and error.
The code might be a little different like some extra numbers, but it almost matches, a little brain work and you'll understand it.