Visual camouflage would be largely worthless in a space environment; I mean, a cap ship could be picked up on radar (or its 27th century, probably tachyon-based equivalent), its engine signature analyzed via the ship's signal and electronic intelligence divisions, and cross-referenced against a database of friendly craft (with the assumption that anything that can't be identified as friendly tagged as a bogey, possibly hostile). WC already has technology in place that does this (IFF Missiles), and also known hostile craft. So well before a ship would enter visual range, you'd a) know it was there and b) if it was a friendly or not. In that environment, paint jobs would be a vanity thing...not a priority during time of war.
Well, first up, notice that radar in WC does not appear to have that huge a range - ships disappear off our radar at about 30,000 kilometres, and while presumably capships have much bigger radar range, we nonetheless witness a few situations where an enemy fleet is able to surprise the enemy by staying undetected until they enter radar range. I would not be surprised, therefore, if radar was augmented by visual searches - if our astronomers today can observe the edges of the our planetary system using telescopes, we can imagine that in the 27th century, there are soldiers using powerful telescopes to observe space around nearby jump points and the like.
Secondly, notice that visual camouflage can in fact sometimes help stay hidden - we see this happen in the WC movie, where the Tiger's Claw hides in a crater. If the Movie Claw were painted a bright green, that might not work so well, right? Similarly, I've pointed out that the black paintjob on the Strakha prototype in WC Academy actually helped a lot.
Thirdly, visual camouflage has more purposes than just remaining undetected. It's also intended to mislead the enemy. Take the situation we see in End Run, for example. Prince Thrakhath receives an intel photo of the Tarawa, and - because it's impossible to determine its size from the photo - he mistakes it for the Concordia. But repainting a ship is not something that can be done overnight (and probably involves a space dock, rather than the crew walking out the airlock with space-paint - though you never know), it takes time. Therefore, the only way Thrakhath could mistake the Tarawa for the Concordia is if a) he know what the Concordia's current paintjob is, and b) the Tarawa was painted similarly.
Finally, while we don't know what paint jobs are used for in the WC universe, we can safely assume one thing: paint jobs are most definitely not a vanity thing. They must serve a practical purpose, for the simple reason that otherwise, nobody would bother with them. Why paint something as huge as a carrier a bright green colour? Paint not only costs money, it also has physical properties like mass - towards the end of WWII, the US Air Force actually stopped painting its bombers, because it was found that an unpainted B-17 bomber, being some 200kg (!!) lighter, could reach higher speeds - and this gave it a bigger advantage than camouflage did. Now, I'm pretty amazed by the fact that the paint on a B-17 added up to 200kg, but apparently that is the case. And if that's the case for a B-17, imagine the situation for a 700 metre-long carrier. We're talking hundreds of tonnes. So, if paint jobs were purely vanity, they would actually be a hindrance to the war effort. We must assume there was a purpose to them.
(and of course, we can imagine various purposes to applying a coat of paint to a ship - the paint could be radar-absorbent, it could be used to strengthen the hull, whatever - what we do not know is why this paint has a specific colour)