Category permalink

I have around 75,000 posts on the site and around 1,000 categories. Normal categories look like domain.com/cat/some_name

What I’d like to do is possibly do a rewrite (or if you know a better way) so that my permalinks look like this: domain.com/read-horror-online-free
Now “read” would be static
“horror” would be the category name
“online-free” would also be static

How can I do this so that it reflects across all my categories?
Thanks for any help guys.