\documentclass{article}
\usepackage{com.braju.graphicalmodels}

\catcode`\@=11%

\pagestyle{empty}

\begin{document}
\TeXtoEPS

\LARGE
\psset{unit=14mm,arrowscale=1.5,linewidth=1.5pt}
\begin{pspicture}(0,8)(0,8)\showgrid
  \SpecialCoor

  


   \rput(2,3){\GM@node[observed=false]{one}} \GM@label[angle=90]{one}{$1$}
   \rput(3,2){\GM@node[observed=false]{two}} \GM@label[angle=0]{two}{$2$}
   \rput(2,1){\GM@node[observed=false]{three}} \GM@label[angle=-90]{three}{$3$}
   \rput(1,2){\GM@node[observed=false]{four}} \GM@label[angle=-180]{four}{$4$}
   
   
   \ncline[arrows=-]{one}{two}
   \ncline[arrows=-]{one}{four}
   \ncline[arrows=-]{two}{four}
   \ncline[arrows=-]{one}{two}
   \ncline[arrows=-]{two}{three}
   \ncline[arrows=-]{three}{four}


\end{pspicture}

\endTeXtoEPS
\end{document}