Sooo, did it work Sethlans? How did you test this after you changed it?
Looking for a way to change my kingdom's color as well...
EDIT:
I tested it to the best of my ability and it seems to work. Would be good to have confirmation though. Changed the color in factions.txt after "0 fac_player_supporters_faction Player's_Supporters 0" as well, but I'm not sure that this was necessary.
And thanks a lot Sethlans! So far it looks cool!