Assuming you're using [url=http://images.fandango.com/images/fandangoblog/GOTG_Bus%20Shelter_Gamora_v6a_lg.jpg]this[/url] Gamora and not [url=http://img3.wikia.nocookie.net/__cb20131121154514/marvel-war-of-heroes/images/2/2f/TrackerGamora4.jpg]this[/url] incarnation...

It looks pretty simple, actually.
Two strips of fabric of appropriate lengths seem to form almost suspenders that connect to her pants and go underneath/behind the waistband.
Then everything is strewn between them. I'd use these parts to turn it form suspenders into a tank-top almost.

[EDIT] I'd sew in a mesh tube-top or something (am not a girl/do not know girl clothes) underneath the suspenders to from the main part.