\def\n{5}
\def\radius{2cm}

\begin{tikzpicture}
	\foreach \i in {1,...,\n} 
		\node[draw, small vertex] (v\i) at ({-360/\n * (\i)}:\radius) {};
		
	\foreach \u in {1,...,\n}
		\foreach \v in {\u,...,\n}
			\draw (v\u) -- (v\v);
\end{tikzpicture}
