From 5.7.0 and forward:
Go to Maintenance | Security Setting | User Maintenance, highlight the user who has part of the group and click Access Information. Here you have different Tabs that show you the user access. On the first Tab 'User Domain Access' click the button User Rights. That will generate a pdf report with all User Rights Assignment by Service Domain for that user.
For 5.6.x:
Go to Report Wizard | Maintenance-Security Settings and choose one of the reports available that satisfy your needs.
It could be 'User Class Rights Assignments' or 'User Srvice Domain-User Class Maint'.
Highlighting each report you can see its description on the right side.