1. First install the EPEL-repositories then install the X Window System

   yum -y install epel-release
   yum -y groupinstall "X Window system"

2. Install the MATE packages. This will take a few minutes

    yum -y groupinstall "MATE Desktop"

3. Tell your system to start the Graphical Interface on boot

   systemctl set-default graphical.target

4. You will most likely want the Gnome Disk Utility as it the easiest way to interface with your disks. This is as simple as a single command. Once installed it can be found in: Applications -> Accessories -> Disks

   yum -y install gnome-disk-utility

Reference: http://45drives.com/wiki/index.php/Installing_MATE_on_CentOS_7