Our soul becomes dyed with the colors of our thoughts.
It is quite a nice metaphor to represents how the way we think affects the way we feel and not the other way around.
On a more spiritual note, a color can trigger an emotion and certain emotions remind us of certain colors.
There is apparently a correlation between the colors you choose to wear on a daily basis and the color of your thoughts.
What color are you wearing right now? It could indicate your current state.