In Korean culture as far as I know the dragons symbolizes a lot of qualities such as the wisdom, longevity, sexuality, fertility, procreation, and regeneration and even devotion, kindness, and gratitude. They are seen as mythical beings having magical powers so maybe the eyes and the colors have something to do with those qualities.
Anyway, I am always curious when it comes to the Japanese, Korean or Asian cultures in general so if you find out more from the monk, you let us know.