Solution
= Solution
The <Cayley graph> $\operatorname{Cay}_S(G)$ is a connected graph with $|G|$ vertices. A shortest path never repeats a vertex, so it has at most $|G|-1$ edges. Therefore
$$
\boxed{\operatorname{diam}_S(G)\leq|G|-1<|G|.}
$$
= Solution
The <Cayley graph> $\operatorname{Cay}_S(G)$ is a connected graph with $|G|$ vertices. A shortest path never repeats a vertex, so it has at most $|G|-1$ edges. Therefore
$$
\boxed{\operatorname{diam}_S(G)\leq|G|-1<|G|.}
$$