You can generate the printed catalog grouped by category.
When doing this it is common to want to order the categories in a specific order. By default the categories will simply be listed in alphabetical order.
If you look at the item category list you will see a Sort Index field that can be used to adjust this ordering:
The categories will be sorted first by sort index, and then by name.
So the categories you want to come first should have a lower sort index defined, and those later a higher one.
You can adjust the adjust the sort index directly from the item categories list (see Edit Rows) or double click on a row to drill to the details.