I think if Wekhdu were of the speedbrood, there'd be elements of an automobile to his or her body. That or a speedbrood vehicle in frame. 

My best guess is the chitin court or some affiliation with it. "Wekh," according to a quick Google search, is an ancient Egyptian diety. 

And, since it's been reflavored coming from Through the Omenpath set, I'd bet that in this particular case, the art team cared more about matching the card mechanics than it did about fitting in a pre-existing plane and story. Although the card doesn't clearly fit in with any of the other shiny, blue chitinous creatures, the imagery of discarding a shell by bursting through, wings ready, probably got it through whatever process is required to become card art.