He didn't say that bats could perceive the separate electromagnetic frequencies corresponding to human colors, he said that bats used textures in the same way that we use colors (e.g. assigning "fuzzy" to "red" and "smooth" to "blue.")
"A discomfiting variety of reallies." Awesome! Dawkins really is more awesome when he's a scientist than when he's commentating on religion--though he's often awesome at that, too. I feel smarter just having watched this video!