If your company need formal auditing for Confluence that includes diagrams within documentation, traceability of who changed what, or you simply don't like what someone else has done to a draw.io diagram
draw.io v3.9.0 introduces in-place preview and restore of revisions for each diagram. Click to edit the diagram and once in the editor select File->Revision History.
You'll be shown a list of all revisions of the diagram
You can select any revision and click preview, this will display the diagram in-place so you can quickly check it.
Selecting and clicking open will replace your diagram of the latest version with a new revision (once you save it).