The purpose of the DocumentsSelector is to provide a user-friendly way of choosing a Guid for a given property. The functionality you are requesting is a bit different (I'm guessing choosing some kind of list of Guids). You are probably right that the naming is a little bit confusing. The good news is that you can fairly easily implement the functionality you want.
Basically you would need to either inherit the DocumentsSelector and override the needed functionality or implement a new Selector. Since you'd probably need multiple selection of items in the UI, starting from scratch might be easier. The end purpose of each selector is to override the Value property of the base class to return what you need - in your case probably a list of Guids.
Here are some resources that will help you get started with WebEditors (selectors):