Three points example.
Four points example.
In this picture you can draw a line to seperate these 3 points in the two dimensional plane to keep points with the same color lie in the same side no matter how to color each point using either blue or red.
But in k dimensional real Euclidean space Rk, can you find n points satisfying that there always exsit a k−1 dimensional hyperplane to seperate them in any one of 2n coloring schemes?