Log in to the Virtual Machines and execute the command:
1.yum -y groupinstall "X Window System" #Install x window package
2.yum -y groupinstall "GNOME Desktop" #Install Gnome package
4.reboot #Server rebooted
After reboot, through the Virtual Machines console, remotely connect to vnc function to log in, you can see the graphical interface as shown:
If your problem still can not solved, please submit open ticket to us.