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.