C.E. Evans wrote:
I always felt that only Starfleet vessels had a particular hull color scheme, but that civilian Federation ships could be any color.
This is pretty much true. It's basically akin to a merchant or private vessel here... some ocean cargo ships have red hulls, while some have green or blue... it depends on the company that owns the vessel. Same with private boats, yachts, or RV's... the owner decides which color(s) they prefer on their vehicle(s).
I would assume the only time there would be a "uniform" color scheme on a non-Starfleet vessel, would be for ships owned by academic institutions, used for research missions or training and the like, as the markings and livery of their given institution would be on the ship.