curl -v -X PROPPATCH -u user@domain:password -H "Depth:0" -H "Content-Type: text/xml" -d "<D:propertyupdate xmlns:D='DAV:' xmlns:P='http://apple.com/ns/ical/'><D:set><D:prop><P:calendar-color>#E346D1</P:calendar-color></D:prop></D:set></D:propertyupdate>" url