Radicale/radicale/tests/static/mkcol_make_calendar.xml

<?xml version="1.0" encoding="utf-8"?>
<D:mkcol xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav">
  <D:set>
    <D:prop>
      <D:resourcetype><collection /><C:calendar /></D:resourcetype>
      <I:calendar-color xmlns:I="http://apple.com/ns/ical/">#BADA55</I:calendar-color>
    </D:prop>
  </D:set>
</D:mkcol>