As adults, panther chameleons are easily sexable as males will display the brilliant colours of their locale, while females will take on a more typical brown/tan/peach/orange colouration regardless of their locale.
Babies are harder to sex, as colourations do not really start to develop until the chameleon is around 6 months. Sexing a male baby can be done by looking for the hemipenal bulge at the base of the tail, which is absent from females from birth. Although this is highly unreliable