\begin{center}
\begin{tikzpicture}[scale=0.2]
\tikzstyle{every node}+=[inner sep=0pt]
\draw [black] (36.9,-7) circle (3);
\draw (36.9,-7) node {$S_3$};
\draw [black] (25.5,-17.2) circle (3);
\draw (25.5,-17.2) node {$E_1O_9$};
\draw [black] (46.6,-17.2) circle (3);
\draw (46.6,-17.2) node {$U_6$};
\draw [black] (16.2,-26.4) circle (3);
\draw (16.2,-26.4) node {$A_2$};
\draw [black] (25.5,-26.4) circle (3);
\draw (25.5,-26.4) node {$I_8N_{10}$};
\draw [black] (34,-26.4) circle (3);
\draw (34,-26.4) node {$Q_5$};
\draw [black] (42.1,-26.4) circle (3);
\draw (42.1,-26.4) node {$T_7$};
\draw [black] (52.4,-26.4) circle (3);
\draw (52.4,-26.4) node {$Y_4$};
\draw [black] (23.37,-19.31) -- (18.33,-24.29);
\draw [black] (25.5,-20.2) -- (25.5,-23.4);
\draw [black] (27.54,-19.4) -- (31.96,-24.2);
\draw [black] (34.66,-9) -- (27.74,-15.2);
\draw [black] (38.97,-9.17) -- (44.53,-15.03);
\draw [black] (45.28,-19.89) -- (43.42,-23.71);
\draw [black] (48.2,-19.74) -- (50.8,-23.86);
\end{tikzpicture}
\end{center}