\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 (0,3.0) {$A$};
\node (B) at (-2.59808,1.5) {$B$};
\node (C) at (-2.59808,-1.5) {$C$};
\node (D) at (-0.0,-3.0) {$D$};
\node (E) at (2.59808,-1.5) {$E$};
\node (F) at (2.59808,1.5) {$F$};
  \end{scope}

  \draw (A) -- (B);
\draw (A) -- (C);
\draw (A) -- (D);
\draw (A) -- (E);
\draw (A) -- (F);
\draw (B) -- (C);
\draw (B) -- (D);
\draw (B) -- (E);
\draw (B) -- (F);
\draw (C) -- (D);
\draw (C) -- (E);
\draw (C) -- (F);
\draw (D) -- (E);
\draw (D) -- (F);
\draw (E) -- (F);

\end{tikzpicture}
