There are five ways to colour the centre square.
Suppose we colour the left hand side. Since the colours of the strip are symmetrical, the number to colour the right hand side is 1.
For the left part where there are 14 squares, let's consider the most adjacent square to the centre. There are four ways to colour that square since it cannot have the same colour as the centre square.
The same goes with the other squares remaining.
So, the answer is 5×4^14.