I don't see how everyone is saying "You can do it in ps_game.exe" or the database. o.O
The blue Admin color is graphical, meaning it's visual, which is where? game.exe in the client. I changed mine on Nightmare through that, and it was somewhat easy to find.
I have some values that were from my game.exe, maybe they'll work for you. You'll have to decipher what I mean, since it was just in my random jotted notes.
Code:
Hex Address 1(GM): Starts on 0004B930 Ends on 0004B9F0 (FF 00 00 FF)
Hex Address 2(GM): 0004B530 (FF 00 00 FF)
If those values don't work for you, use HxD and search for this pattern of Hex values:
Code:
C7 44 24 14 FF0000FF
To edit (I believe, I didn't jot this down in my notes), the format is ARGB (Alpha Red Green Blue) - I suppose just leave Alpha as FF, and use a HTML color palette for the other 3. Good luck.