Females change color for various reasons:
a) They're scared, in which case, they pale up and gain lateral horizontal bars.
B) They're stressed, and then they also pale up and gain lateral horizontal bars.
c) They're calm and in good, clean water. Then they can attain colors just as bright and vibrant as their male counterparts, with no lateral bars.
d) They want to express their dominance over another female. They attain their bright, vibrant natural color, and they gain lateral vertical bars.
e) They want to breed. They attain their bright, vibrant colors, gain their lateral vertical bars, and most times, will show lighter coloring behind their head, underneath the pectoral fins, but above the ventral fins.
Could any of THAT explain your females' coloring?
Edit: Forgot to mention that all of these color changes can happen quasi-instantaneously.