When the female shows the dark background colors, hisses, sways back and forth, gapes, lunges at the male, etc. she is telling the male she is not receptive or already gravid.
If she behaves calmly, keeps her green coloration (with blue dots and mustardy colored splotches), does not hiss, does not gape and moves away from the male slowly she is receptive.
If they have been housed together for some time after reaching sexual maturity she will be producing fertile eggs. They should only have been housed together to mate once they are past 3 month of age and not left together, as was already said.
She needs a place (opaque container at least 12" x 12" x8" deep filled almost full of washed playsand) in her cage to dig in so she can show you she's ready to lay the eggs. This place to dig should be in the female's cage once she reaches sexual maturity and only removed to dig up eggs should she lay them there. I have a 65 liter bin that I move the female to once she is digging intently if I feel that she is not happy with this small container in her cage.