Ardeth Kapp, a former general Young Women president, says that the colors used to represent the values have no significant religious meaning. They are meant as reminders.
White is symbolic of purity and Faith.
Divine Nature seems to suggest creation, the big blue sky, and all that is divine.
Individual Worth should be bold and confident. Red fit that feeling.
Knowledge is symbolic of green and growing.
Choice and Accountability, two values together, is represented by putting two colors together; red and yellow make orange.
Good Works brings sunshine, happiness, and light. Yellow seemed to fit.
And Integrity is purple, royal and righteous.
(ADD LATER not by Ardeth Kapp) )Like the gold Peruvian shawl the Young Women presidency unfurled at the top of Ensign Peak, the value of Virtue will be represented by gold — a precious metal that has long been known as a symbol of purity, said Sister Dalton. “When gold is refined, it is pure,” she said.
“If you are virtuous, you are strong,” added Sister Cook. “It is power and it is strength. It is all derived by being pure.”
Sister Dibb noted that virtue is “what’s a part of you that no one else will know. But you know and the Lord knows.”
Sister Dalton compared gaining virtue to training for a marathon. “Virtue isn’t something that you have instantly,” she said. “It is strict training. It is the daily, deliberate practice of small things.”
http://www.lds.org/pa/library/0,17905,5072-1,00.html
In December 2008 they added a new value, the 8th value is Virtue:
The time has come for the young women of the Church to lead the world in a return to virtue. This is the time to be pure and to qualify for the guidance of the Holy Ghost. In the coming year, it is our desire that all young women and their leaders focus on the meaning of virtue, what young women can do to accept and act upon this value, and how this attribute can strengthen young women as they prepare to be worthy to make and keep sacred covenants and receive temple ordinances.