Role and user auditing

Summary

How to track role assignment and role removal dates

Content

Hello, 

I have a requirement at my customer place that we are able to find the history of all the users role assignment and role removals.

Oracle doesnt keep this information in any of the cloud table. Once role is removed, there is no trail left if the user had any role assigned. I know we can enable the role auditing but the audit report is not user friendly.

Every SOX audit will look for the trail of the role assignment and removals. Wanted to get suggestions from everyone how are you managing this at your place?