Magento Enterprise has this functionality built-in.
Click System > Configuration
Select Default Store Scope (which is selected by Default)
Click Catalog in left menu
Select Category Permissions > set to Yes
This will turn on category permissions for all Store Scopes, so be sure to select “Yes, for Everyone” for Allow Browsing Category, Display Product Prices, Allow Adding To Cart. Otherwise, all your categories will be restricted to everyone!
Then save the Default configuration. Now you can set each of your individual store scopes to have Category Permissions by Customer Group. So now go to Catalog > Categories and select a Category or SubCategory. You will now see a new tab called Category Permissions. Wow!
Now you can select which Customer Groups are allowed to view which Categories / SubCats using a rules based config.
I’ve never used Community so I don’t know if the procedure is the same. Hope this helps !