I don’t believe there’s any Entity Relationship Diagrams in IFS documentation, so you’d have to find some kind of tool to map it out for you. Partly, this was always explained as being due to the modular nature of IFS. I would guess a tool like this exists but with IFS using Views to present data to users and a lot of similarity between Views this would be incredibly large and messy, and if you only mapped the Tables you’d be at serious risk of confusion.
Also, depending on the IFS version and on-prem vs hosted Cloud, an ERD is likely less helpful than it used to be with it being driven via RestAPIs now rather than in the past where it was all database APIs and in general a more common approach of using DB calls and read/writes.
Certainly it would be nice and a lot of customers used to ask for it, and finding relationships can be slow going, but if I was starting with IFS Cloud I’d be far less inclined to use that and would be more interested in the API Explorer. No diagrams there, but the documentation is pretty comprehensive.
It will be difficult to find any tool to visualize this. It's important to remember that IFS doesn't use foreign keys. If such a tool exists, it must read information from Reference_sys_tab.