Why is the dragon in Four Holy Beasts not a direct dragon?

Zuo Qinglong, Right White Tiger, Upper Suzaku, Lower Xuanwu

That is, the east is Qinglong Star, the west is White Tiger Star, the south is Suzaku Star, and the north is Xuanwu Star (a snake wrapped around a giant turtle) (because it is a celestial phenomenon, it is opposite to the position on the ground, not left, west, right, east, north and south).

This is the ancient astrological orientation of China, similar to the constellation of ancient Greece.

At the same time, color is also called by a name. I suggest you look at China's ancient astrological works, or there are introductions in the mirror.