A race's sensitivity off the ends of the spectrum should effectively give them more colors to describe. The farther out you go, the more colors you get. If you're truly color-blind then all you get are shades, without even a concept of "color". Either of these has serious implications for cultural systems.
Here on earth we're very well adapted to the peak of sunlight. The sun's energy peaks at green and that's where our vision is most sensitive. If your star is red and your race has color vision then they will likely have a set of "colors" that humans would see as "red" or be totally insensitive to. Similarly, a race with a bluer star will probably tend to have their colors higher up in the spectrum, probably with an extra color or so in the UV and perhaps be missing a color or two in the red.
Color vision in humans follows a tri-stimulus model with a panchromatic base element. That is, there are three types of color sensors (called cones), each sensitive to different parts of the spectrum and one type of sensor (rods) that respond to the whole visual spectrum. Some things to consider:
(1) Color vision is slightly less acute than pure monochromatic vision. This result comes from the fact that cones are slightly larger than rods and from the need to mix cones of multiple types to get vision across the full spectrum range. If you need to add more types of "cones" to get farther out on the vision scale then visual acuity might decrease.
(2) Color vision needs more light to work. You can see this as light in the room gets lower at dusk. The world goes toward a grayer, grainier version as the world gets darker. Similarly, when you're outside looking at stars you're better off averting your gaze slightly to get the starlight to fall on the more-sensitive rods around the foveola.
(3) Light sensors are most concentrated at the primary focus of the lens get less concetrated the farther away from the center you get. In humans, the fovea is stuffed with cones, giving good color vision. There are fewer cones as you get farther away from the fovea and proportionally more rods. This means that your peripheral vision is lower acuity in both a spatial sense and in a color sense. The arrangement of light sensors works well at reducing the total amount of information that the brain has to process while still giving good results.
(4) Color blindness in humans tends to be more a result of defective cones of one or more types rather than the absence of those rods. People with color blindness may have somewhat lower visual acuity than someone with a full complement of vision.
(5) Visual predators tend to have a much greater visual acuity. In some species this acuity comes about by sacrifice of color vision. In others there are special structures to increase acuity (look at a raptor's eye).
As an aside, modeling color differences with a graphics program doesn't really "mean much" in absolute terms. For example, I can pull the IR filter off my webcam to get it to see farther into the IR spectrum. What I see on my screen is a strange pink image, not new colors as you would expect for a race that is actually sensitive to those parts fo the spectrum.
Mapping "new" parts of the spectrum into our "regular" part of the spectrum doesn't do much for me. Consider http://apod.nasa.gov/apod/ap070505.html as an example. It's nice that they can assign X-ray parts of the spectrum to "blue", visible parts to "green", and IR parts to "red" to get a new image that tries to take advantage of your color vision. The result is somewhat pretty but seems to just be a curiosity.
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Originally Posted by Redrobes
