Question: What do the colors on the card mean?

Answer: The colors on the card represent how many suits are needed in the hand. It doesn’t matter which color represents which suit. If there are two colors shown, it means that you can choose any two of the 3 suits. Always read what is in parentheses after the hand as this information may supersede the colors shown. For example, there might be one color shown for the hand but in parentheses it might say, “Any Dragon.” In this case, it would indicate the Dragon does not need to match the suit. 

Source: Mah Jongg Made Easy 2024, page 12, CHOOSING A HAND