She's naked (at least topless) in that scene; she's looking over her shoulder at *somebody* (probably Quill) with a come-hither glance, and she's making no attempts at modesty or covering herself. That's about as sensual as it gets.
And anyways, it's Gamora, fer cryin' out loud. Yes, we get these "objectifying! sexism! body image!" rants every time we get a new female character in these movies, with varying degrees of accuracy in those arguments. In the case of Gamora, it's *entirely* within her character to have a voracious sexual appetite. I wouldn't expect anything less from her.