Advice for a good sitemap structure

Who can me explain sitemaps?
I am interested in the more complexed structure.

For example: on the homepage I have hyperlink to a page with categories
A category can have a subcategory or a product.

The url structure look like this

And so one.

What is a good structure for the sitemap?

I know the structure of a simple sitemap.
But it are many urls…

Do I create an index sitemap with and split up everything like a sitemap for the homepage
One sitemap for the categories and one for the products?