Why not. Just because we can't see it directly doesn't mean it cannot be seen and interpreted by our sensors.
Color is just a word we came up with to describe certain wavelengths in the light spectrum. But colors are named based on what we see. Therefore, any light in the non-visible spectrum has no color.
For another example, think of it this way. Would you say water (pure water, of course) or air has color? No, of course not. However, if we were to magnify the water or air under a microscope down to the molecular or anatomical level, you'd mostly likely see colors. If that's the case, and they really do have color, why do we say they have no color? It's simply because color is a word, made by humans, defining something in the visual realm. Thus, if we can't see it, it is colorless.
If for some reason you're still not convinced, here's the definition of color:
1. the property possessed by an object of producing different sensations
on the eye as a result of the way the object reflects or emits light.
And there you have it.
