Are there files for correct signal colors? If not what are the correct colors?
The signal lamp color hues are set in the sigcfg.dat file. It's hard to publish "files" correcting them because each route's sigcfg.dat is often custom-made for the route. What really needs to happen is the colors get fixed before the route is published!
There are also no firm and correct color hues for signal colors in the game. In the real world, signal colors are regulated, but each standard is an acceptable range. The age and design of the signal and the lenses also matter. What looks right on one type of signal on one route might not be quite right for another signal design or another route. Because color is so complicated to quantify in the real world, it's even harder to come up with in-game numbers that are assuredly accurate.
I've recently setup a web page talking about this: Just Say NO to Lime Green Signals!
The color values I give on that site I've developed over time and are what I've chosen to use in most situations. I think they look pretty good. But those values are still suggestions. If you feel the need to try to tweak them to your own taste, go ahead. Just don't go back to that default lime green!
Thanks. I only have one signaled route at the moment as the other two are not ready for that yet, I used Hanks Searchlight signals and they were closer to reality than the default ones.