\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)(10,8)%\showgrid
  \SpecialCoor

  \rput(5,5){\GM@node[observed=false]{Y}} \GM@label[angle=-180]{Y}{$Y$}

  \rput(5,3){\GM@node[observed=true]{x1}} \GM@label[angle=-90]{x1}{$X_1$}
  \rput(2,2){\GM@node[observed=true]{x2}} \GM@label[angle=-180]{x2}{$X_2$}
  \rput(8,2){\GM@node[observed=true]{x3}} \GM@label[angle=0]{x3}{$X_3$}
  \rput(5,1){\GM@node[observed=true]{x4}} \GM@label[angle=-180]{x4}{$X_4$}


  \ncline[arrows=->]{Y}{x1}
  \ncline[arrows=->]{Y}{x2}
  \ncline[arrows=->]{Y}{x3}
  \ncarc[arcangle=-60,arrows=->]{Y}{x4}

  \ncline[arrows=->]{x1}{x2} \ncline[arrows=->]{x1}{x3}
  \ncline[arrows=->]{x3}{x4}
\end{pspicture}

\endTeXtoEPS
\end{document}