I think this is Kakumi Saya, but there's a few weird things about it.
She's the only one I can see from the Xipuria cast that has that floating orange thing behind her, and the costume is a pretty close match to her profile on the Twitter account.

However, she lacks the same hairstyle as her normal self; while posts like 3755292 show her with long hair, this picture lacks the orange stripe. So maybe it's supposed to be Reina? Granted, Reina's hair is supposed to be purple, but she has been drawn with more white hair by the same artist, and the front part of the hair would match better if it was her...

Given the lack of cosplay artwork for Xipuria and in lieu of more information, I've tagged this picture as Kakumi Saya with an alternate hairstyle instead of Reina with an alternate outfit.