During the end of the plants life cycle you will see lots of vibrant colors.
Ever look at trees in the fall? All the leaves turn yellow, red, well this is basically the same thing that happens to Cannabis. When they flower, the plant things its life is ending soon. The plant basically think's its entering fall season, it will change color leaves, they will fall off, and you are now at your harvest window.
Leaves in your photo look very crispy as well. Does your light have a good distance between the plant? Looks like it may be a little close, again just a guess.
Another thing to remember when you see these colors is to be mindful of your flush. Did you start your flush yet? If so this could have kickstarted your color change as the flush removes salts and other minerals such as Nitrogen. Once this is removed you will see a rapid change in color and is helpful for creating a smooth smoke!
Hope this helps!