White is used as a symbol for purity. You will see white used on occasions that commemorate Christ's life on earth, like Christmas, Easter, and Ephiphany. The purity of white is appropriate for new birth, and therefore is used for baptism. It is also used for other important events in the lives of people, such as weddings and funerals. White is the presence of all colors.
Red is used to symbolize both the fire of the Holy Spirit and martyrdom. Since it is also the frequent color of choice for ordinations and consecrations, one is left somewhat confused as to whether the red is symbolic of the descent of the Hold Spirit upon the newly ordained or the new bishop, or in anticipation of a new church martyr.
Purple is used for penitence and to indicate sorrow. However, purple is also used as a symbol for royalty.
Green is the symbol of life. It is also the symbol for growth, fertility, and spring.
Blue is also used as a symbol for penitence. No one is quite certain whether blue or purple provides a more meaningful outward sign of a contrite spirit. However, blue is also used for penitential preparation, as during Advent. It is also traditionally the color assigned to the Virgin Mary.
The color "rose" is used for the Fourth Sunday in Lent and Third Sunday in Advent.