My two WTF do the same thing. In the day they hide under leaf litter, and turn brown. At night they emerge, become active, and turn green. I feed them and I can hear them jumping around in the evening. They go down to the water area to soak a little then they go up under the basking light for a while and in the morning they're back to hiding under leaf litter and turn brown again.

One frog does this 100% of the time, the other some times will just chill out in the open during the day half the time.

Day temp 80F
Night temp 75F
Humidity ~60%