The yum group "XFCE" requires the package xfce-utils, however this package is no longer available in EPEL 7
Filed https://pagure.io/fedora-comps/pull-request/331 to fix this.
This was merged, so tomorrows epel7 compose should update comps.
Thanks for the report!
Metadata Update from @kevin: - Issue close_status updated to: Fixed - Issue status updated to: Closed (was: Open)