Red
Red represent zeal, eagerness and passion for life and for dealing with it and its many challenges. Cards which has a predominant color of red (e.g. the Emperor) reveals a persons’ behavior towards life and his attitude on approaching it.
Orange
Red and orange are somewhat adjacent in the color spectrum thus orange also signifies passion and enthusiasm with approaching life. Compared with red, though, cards with prevalent orange color signifies zeal and enthusiasm in lesser degree than red.
Yellow
Yellow represents intellectual ability and signifies a person’s tendency to approach life and its various challenges intelligently. Cards which feature yellow as the predominant color (e.g. the Sun and the Strength) signifies curiosity over life as well as a person's tendency to act on logic and reason based from analysis.
Green
Green is the color of nature. It represents harmony and balance and cards with green signifies a holistic approach to life (zeal, intellect, caution, compassion and purity). In the Rider Waite Deck, though, cards with predominant green color are rare.
Blue
Blue signifies the spiritual aspect and its realm. Furthermore, color blue represents a balanced understanding of the spiritual aspect. Cards with the predominant blue color signify spiritual intelligence, which enables a person to survive and go through life in a completely new level.