can u make a cinematic for diana

The vast majority of champions don't have a cinematic.

Cinematics are very demanding on time, resource, and man power. They can't make many of them and not every character will get to be in one. It would not make sense to give Diana a cinematic unless you had a specific story you wanted to tell through a cinematic medium and found it particularly valuable to do so. "Diana has no cinematic video" is not enough of a reason because you need to justify why a cinematic should be made for her rather than a single unpunctuated sentence explaining how she, like most characters, does not have a cinematic video.