So I perused some Valve maps and this is what I found: (I only looked at 5-poin CP maps, because that's what mine is):
On a team's side, they have signs of that color pointing to all their battlements, cp's, resupply rooms, etc.
There are also sometimes large arrows that point towards the center. They are there mainly to help people of that team.
There are also signs of that color pointing to the center CP.
Only Granary has oppositely-colored signs on the other team's half of the map, but they are placed so only the attackers would see them.
Also, none of the signs are dynamic, i.e. they don't change color when you cap a point.