Suppose you had two intelligent species that came together and built a society or whatever. For the sake of example, we'll call them species A and species B. Species A evolved to see some subset of the visible light spectrum (or all of it), and can distinguish various "colors" in that range due to having multiple types of cones with varying sensitivities to radiation in their visible range.
Species B evolved a different range of visible radiation, but can also discern "color" within that range using similar biological features. Maybe they see into ultraviolet or infrared radiation. They might have some overlap with species A's spectral range for vision, but perhaps the two are entirely disjoint- though not terribly far apart.
What sorts of difficulties would arise from these two species trying to cooperate and communicate?