VERTEX COLORING
A graphical solution
Instructions
Draw a graph
*Doubleclick on the canvas to draw a vertex.
*Click on the first vertex and drag the mouse pointer to the second vertex to draw an edge between them.
*To clear the canvas click on "clear" button.
Note
*If you are using chrome browser, then just give a single click on vertex before drawing edges.
*Maximum of 10 colors allowed.