The graph is a simple path graph, where each vertex is connected to at most two other vertices. Since a path graph is a bipartite graph, the chromatic number is 2. However, in this specific case, there are 5 vertices, and since each vertex is connected to at least one other vertex, we would need 3 colors to ensure no two adjacent vertices have the same color.
Thus, the minimum number of colours required is \( 3 \).