\documentclass{article}
\usepackage{com.braju.graphicalmodels}
\usepackage{amsmath}
% \special{papersize=40mm,80mm}
% \setlength{\pdfpagewidth}{40mm}
% \setlength{\pdfpageheight}{80mm}
% \usepackage[vcentering,dvips]{geometry}
% \geometry{papersize={80mm,120mm},total={80mm,120mm},margin=0mm}



\catcode`\@=11%

\pagestyle{empty}

\begin{document}
\TeXtoEPS

\LARGE
\psset{unit=10mm,arrowscale=1.5,linewidth=1.5pt}

\begin{pspicture}(-0.5,0)(5,7)
  \SpecialCoor

  \rput(1,1){\GM@node[observed=true]{y_i}}
  \GM@label[angle=-90]{y_i}{$y_i$}

  \rput(3,1){\GM@node[observed=true]{x_i}}
  \GM@label[angle=-90]{x_i}{$\boldsymbol{x}_i$}
  
  \rput(2,3){\GM@node{z_i}}
  \GM@label[angle=90]{z_i}{$\boldsymbol{z}_i$}

  \rput(1,5){\GM@node{w_y}}
  \GM@label[angle=90]{w_y}{$\boldsymbol{w}_y$}
  
  \rput(3,5){\GM@node{W_x}}
  \GM@label[angle=90]{W_x}{$\boldsymbol{W}_x$}

  \rput(-0.3,  0){\GM@plate{4.6}{4}{N}}
%  \rput(-0.3,4.3){\GM@plate{4.6}{2}{L}}

  \ncline[arrows=->]{w_y}{y_i}
  \ncline[arrows=->]{W_x}{x_i}
  \ncline[arrows=->]{z_i}{y_i}
  \ncline[arrows=->]{z_i}{x_i}

\end{pspicture}

\endTeXtoEPS
\end{document}