<iframe frameborder="0" style="width:100%;height:926px;" src="https://www.draw.io/?lightbox=1&highlight=0000ff&page=3&edit=[linktoeditfile]&layers=1&nav=3&title=[linktodiagramwouldbehere]"></iframe>
Note, if you want them to be able to edit the diagram directly when generating the publish link or html code you have to change the edit option to custom and just hit ok on the link that pops up by default. Otherwise it will create copies for them to edit.