\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}(0,0)(9,4)
  \SpecialCoor

  \rput(1,3){\pnode{x_tm1}}
  \rput(3,3){\rnode{x_t}{$x_t$}}
  \rput(6,3){\rnode{x_tp1}{$x_{t+1}$}}
  \rput(8,3){\pnode{x_tp2}}
  \rput(3,1){\rnode{v_t}{$\boldsymbol{v}_t$}}
  \rput(6,1){\rnode{v_tp1}{$\boldsymbol{v}_{t+1}$}}
  
  \psset{arrows=->,nodesep=3pt,linecolor=black}
  \ncline{x_t}{v_t}
  \ncline{x_t}{x_tp1}    \naput{\Large $\psi_{t,t+1}$}
  \ncline{x_tp1}{v_tp1}
  
  \blue\Large
  \psset{arrows=->,nodesep=6pt,linecolor=blue}
  \ncline[offset=-8pt]{v_t}{x_t}     \nbput{$\psi_t$}
  \ncline[offset=-8pt]{v_tp1}{x_tp1} \nbput{$\psi_{t+1}$}
  \ncline[offset=8pt]{x_tm1}{x_t}    \naput{$f_t$} 
  \ncline[offset=-8pt]{x_tp2}{x_tp1} \nbput{$\beta_{t+1}$}
  
\end{pspicture}

\endTeXtoEPS
\end{document}