\begin{tikzpicture}
    \foreach \pos [count=\xi] in { (1, 3), (2.5,4), (0, 2), (3, 2), (-1, 5), (1, 6), (-1.5, 3) }
		\node[vertex] (v-\xi) at \pos {$\xi$};
	
	\foreach \v/\u in {1/2,1/6,1/5,2/5,2/6,5/6}
        \draw[thick] (v-\v) -- (v-\u);

    \foreach \u in {1,...,6} \draw[red, thick] (v-7) -- (v-\u);

	\foreach \v/\u in {1/4,3/4,3/5,2/4}
		\draw (v-\v) -- (v-\u);
\end{tikzpicture}