I haven't installed any graphical interface like X Window on Centos, and found its solution how to install it for my personal purpose. Please take a look below steps to install "Gnome Shell" as a main graphical interface.
STEP 1. Install X Window System
yum groupinstall "X Window System"
STEP 2. To add the Gnome Shell desktop on CentOS 7, you would do:
yum install gnome-classic-session gnome-terminal nautilus-open-terminal control-center liberation-mono-fonts
This would provide you with a minimal Gnome Desktop environment. You do have to do a couple of other steps:
unlink /etc/systemd/system/default.target ln -sf /lib/systemd/system/graphical.target / /etc/systemd/system/default.target
This will allow it to start on boot as you are setting it for the default boot target runlevel.