The colors of dragons in Eastern mythology have varied and complex meanings. According to the Five Element Theory (wood, fire, earth, metal and water) presented by nationsonline.org, the symbolism of colors is determined largely by the element category in which they are found.
Originally only two colors were used -- black and white -- constituting the yin-yang philosophy of "opposing, yet complementary principles." With the acceptance of the Five Element Theory, the basic color wheel was enlarged to include red, green and yellow. Chinese Taoistic thought has it that when those five intensities are "in motion," the mixing of colors occurs, leading to combined interpretations.