The 486 exam is not just about UML, which is IMO just a small, almost incidental, part of the exam. The main focus is Object-Oriented Design.
Two years ago when I took the exam, the recommended reading was Craig Larman's book on Applying UML, OOAD and Design
Patterns + UML Distilled by Martin Fowler. It may be possible for someone with no practical experience with OOAD to read the books, internalize the concepts, and pass the exam but IMO, it would be highly improbable. There were a number of posts in the past that discussed a number of questions from the practice
test that used to be freely available from the IBM website. Try searching for "ICE" and "486" in this forum to try dig those old threads up. If you can follow the various discussions then you may have a shot at passing.
Also, you may want to guage your readiness by taking the pre-certification test, although as I understand, it is no longer free of charge.