You should be able to do that with Powercli, you can query the roles and their assignments
I've made a script once to query all roles and thei assignments exporting to CSV/excel with an output similar to this:

(it's just a small piece of the output)
"on Datacenters" means the permission is assigned on the vCenter level, in case you have an assignment on a VM level you will get there a name of the VM/other object.