There is no way to group by category automatically however you could use the shortcode with the category shortcode option multiple times on the same page to manually group them.
This will work fine if you have a smallish directory of individuals (20–40, max 50’ish). However, search and the category filter would not provide a good user experience (they are off by default in Gridder).
If you opt to use the category shortcode option, you will also have to make use of the home_id shortcode option. If you do not, when you click the entry’s profile link you would see the entry listed once for each time you used the shortcode to group the categories. How to set this up…
Create a second page named “Person” (the name is not important, it can be anything), add the
[connections] shortcode to it without any options. Take note of the Page ID. On the original page, add the
home_id=x to each instance of the shortcode where x would equal the Page ID of the “Person” page. After you do that, all links will now resolve to the “Person” page.
Hope that helps!