The tail is slender & whip like, the stomach has noticeable curve's. A male's stomach generally is flat with tail, the hemipenile bulge & more muscular (more so as they mature) tail gives an undeviating line from stomach too tip of tail.
Other things that indicate a female is less prominent rostral process (nose overhang), colour generally comes in around 6 to 12 months. Females i know from first hand experience can be super colourful when juvenile too so cant be relied on consistently