When a contact list is displayed (excluding group or account contact lists), the Groups command does display the accounts and groups. The display shows for each account group names and number of contacts in each group.
When a group is not empty, touching the name of the group do display a list of contacts in the group. Similarly, touching the name of an account, you see a list of contacts who have an elementary contact in the account.
For empty group, touching line icons allows to create a contact for the group, or search an existing contact to add to the group.