\newcommand{\arrow}[2]{\path [-{Latex[scale=1]}] (#1) edge (#2);}

\begin{tikzpicture}

  \begin{scope}[every node/.style={shape=circle, fill=white, draw, inner sep=2pt}]
    \node (A) at (0,4.0) {$A$};
\node (B) at (-2.82843,2.82843) {$B$};
\node (C) at (-4.0,0.0) {$C$};
\node (D) at (-2.82843,-2.82843) {$D$};
\node (E) at (-0.0,-4.0) {$E$};
\node (F) at (2.82843,-2.82843) {$F$};
\node (G) at (4.0,-0.0) {$G$};
\node (H) at (2.82843,2.82843) {$H$};
  \end{scope}

  \begin{scope}[every draw/.style={}]
    \draw (A) -- (B);
\draw (A) -- (C);
\draw (A) -- (H);
\draw (B) -- (C);
\draw (B) -- (F);
\draw (C) -- (D);
\draw (C) -- (H);
\draw (D) -- (E);
\draw (D) -- (F);
\draw (D) -- (G);
\draw (F) -- (G);
  \end{scope}

\end{tikzpicture}