When last we saw the Gods of Literacy, they were grabbing onto the legs of Anansi, as he gave them his stories. These words were bring channeled right into the glyphs, cuneiforms, hieroglyphs and other letter forms of each culture. So…since Anansi and his arms were going to be white (to stand out against the multi-colored images of the gods, and to make the connection visually obvious) then all the letters had to be white too.