Here someone made a custom cover for the STEAM version:
-> http://www.steamgamecovers.com/covers/injustice-2/4799
Is this what you are looking for, except with Xbox instead of Steam banners / logo?
Yeah, kinda! It'd just need to be edited a bit, of course. Make it the size of an Xbox One cover if it isn't already, remove the 'Not for Resale' box thing, as that just looks unappealing to be completely honest. Any and all things on there that relates to the PC version of the game, as it wouldn't make sense for that to be on an Xbox One cover as you've pointed out.
Though just to be clear, if you didn't know, the covers don't have an 'Xbox One' logo on the top of the cover or anything, that's already on the case.
Here's a scan of the back on the Xbox One copy I found, you can use it to get the stuff needed. Really, all you need is the information on the back
https://cdn.shopify.com/s/files/1/0730/3461/products/Injustice_2_Xbox_One_2_Back_Pegi_RL71ZN5M9YLM.jpg?v=1507611511Sorry if this sounds like a jumbled up mess, I'm not good at explaining things, especially things I have no idea on how to really do. Well, properly, at least?
Basically, remove the STEAM/PC shit, replace it with Xbox One shit, if you use the scan of the back I sent you, replace all the EU shit with US shit, maybe resize it so it'll fit into an Xbox One case if it doesn't already, make sure it's not blurry, or not too blurry, at least.
...Does that help?