Split my post sitemap into post categories

Hi, I would like to split the post sitemap into post categories.

I want to split my current post.xml that shows:
https://mywebsite/cat1/post1
https://mywebsite/cat1/post2
https://mywebsite/cat2/post3
https://mywebsite/cat3/post4

And replace it by separate post sitemaps for each category:
cat1-posts.xml
cat2-posts.xml
cat3-posts.xml

Can you help me?