Where and how would you read those audit-trails?
Perhaps a log file would just be the easiest way of doing that.
Of course all this information is contained in the neo4j-logical logs, but there is no officially accessible reader for that.
Otherwise you can register a TransactionEventHandler on the GraphDatabaseService that can intercept and check all modifications and write them to wherever is suitable (the graph - e.g. a secondary linked list structure attached to each node) another kind of database or a regular text file.
Michael