Stan said:
Can you expand a little bit. What exactly do you mean by "graph
representation of an XML Schema"? What would you like to see in that graph?
And do you really mean graph as in graphical, or graph as in data
structure, or graph as in state machine for the grammar.
Many XML parsers which support schemas can be asked to pass you their
data structures describing the schema; those are often what they use to
build their own state machines. I don't know of any which provide a
graphical rendering thereof.