The attached slides date back to 2006 but have helped me more than once and they still do.
They describe the objects used in standard SAP E-Recruiting and their relationships that connect them.
It also features a slide with the infotypes where the data of these objects are stored.
At our company we call it the uber slide because it’s the best slide(s) ever created by SAP.
They might not contain all the new features added in the latest Enhancement Packages but it’s a great base to start with!
You can also refer to the eRecruiting Wiki: E-Rec Infotypes and Relationship between them – ERP Human Capital Management – SCN Wiki