How does the author use colors to represent tribal affiliations in the novel, Escaping Peril?

The author uses colors to symbolize tribal affiliations. NightWings, for example, are dark shades of blues and greens that tend to look black except in direct sunlight. When Peril is looking at the town of Possibility from a distance, she notes that she cannot tell what color each dragon is, which symbolizes the fact that all tribes live together in Possibility.