The syllabus for Bank PO and Management entrance exams are more or less the same, the only difference is the question pattern. If you go through SBI PO questions you'll realize they have quite increased their level of difficulty similar to that of CAT or XAT. 

So read the same material for both PO and XAT exam, but just go through the pattern of questions once so you can clear both the exams. 

One thing that you'll need to focus on in XAT exam is that they ask a lot of cases based questions where they'll provide you an organization scenario and you'll have to answer the decision you'll take. 

All the very best