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

\catcode`\@=11%

\pagestyle{empty}

\begin{document}
\TeXtoEPS

\LARGE
\psset{unit=10mm,arrowscale=1.5,linewidth=1.5pt}
\begin{pspicture}(0,0)(6,8)%\showgrid
  \SpecialCoor


  \rput(1,3){\GM@node[observed=false]{z31}} \GM@label[angle=-45]{z31}{$x_{3,1}$}
  \rput(3,3){\GM@node[observed=false]{z32}} \GM@label[angle=-45]{z32}{$x_{3,2}$}
  \rput(5,3){\GM@node[observed=false]{z33}} \GM@label[angle=-45]{z33}{$x_{3,3}$}

  \rput(1,5){\GM@node[observed=false]{z21}} \GM@label[angle=-45]{z21}{$x_{2,1}$}
  \rput(3,5){\GM@node[observed=false]{z22}} \GM@label[angle=-45]{z22}{$x_{2,2}$}
  \rput(5,5){\GM@node[observed=false]{z23}} \GM@label[angle=-45]{z23}{$x_{2,3}$}

  \rput(1,7){\GM@node[observed=false]{z11}} \GM@label[angle=-45]{z11}{$x_{1,1}$}
  \rput(3,7){\GM@node[observed=false]{z12}} \GM@label[angle=-45]{z12}{$x_{1,2}$}
  \rput(5,7){\GM@node[observed=false]{z13}} \GM@label[angle=-45]{z13}{$x_{1,3}$}



\end{pspicture}

\endTeXtoEPS
\end{document}