A dominant female (of just about any cichlid) may show a more male like color pattern, even to enclude a nuchal hump type profile.
Here is another species of cichlid example, below a female haitiensus in the dominant mode (no male in the tank).
Below, Her normal color, and profile (with a dominant male in her tank)
But there is one caveat, a subordinate male cichlid, in the presence of an very alpha male, may also sport female color, and less steep profile. So its possible for one to "not" always be 100% sure.
Another example when the cichlids are actually spawning, take the carpintus below.
The males in normal color
but when spawning, he adapts female coloration, to include dark pigment in the dorsal