A quick fed fighter retex.
You'll notice that the fighter uses red trim, and all the starships use blue. You see, in my private little star trek universe, I always imagined Starfleet as more military than paramilitary. In keeping with that, different branches get different colors. Blue = navy, red = starfighter corps, etc, etc.
I also rather think of the federation less as a centralized governemnt, and more like the real-life UN or NATO. It's an alliance where various members contribute resources and mutual defense, but are definitely sovereign within the membership. (this is why, if you notice, all my "federation" ships are actually from Earth and have the "United Earth" signage on it.)