category list format

I did a search about this but didn’t find what I needed. The category list on my sidebar looks like this:

Category
-subcat
-subcat
-subcat
Category
-subcat
-subcat
etc.

I used the wp_list_cats tag. however, I want it to look like this:

-Category: sub, sub, sub, sub, sub
-Category: sub, sub, sub, sub, sub
-Category: sub, sub, sub, sub, sub
etc.

I looked through the category tags pages and tried some stuff but couldn’t seem to find anything that would do it. I’m not an expert at coding so it’d be great if you could explain what to do, thanks. 🙂