I don't know if it's Star Trek Cannon, but there was a novel where it is discovered that Klingons can't see into the red spectrum and have Amber Alert instead of Red Alert in emergencies.
I just did a quick search, and can't find the book it was in. I did find some posts on the subject in Reddit that talk about Klingons seeing further into the red and don't see much into the green spectrum due to their sun & atmospheric conditions of their home planet.
I would guess that Vargr in Imperial space, especially on military ships or bases, would have lighting in a spectrum they could see denoting the Green, Yellow, and Red that are seen by humans in emergencies.