Groups / Roles in organizational Chars

Hi

We are building an enterprise identity and access management. For that purpose I I want to build an overall organisational chart that contains all the roles. These roles are organised in groups, so I want to put the groups in the org chart. I have been told not to put the groups as roles, but as groups. But how can I add the groups to the org chart?

Also it seems not usual to put roles into org charts. So what would then be the place to design a role model?

Thanks and regards

Bertin