M-DAG.tex

\documentclass[tikz, border=2pt]{standalone}
% main document, called main.tex
\usepackage{tikz}
\begin{document}

\usetikzlibrary{fit,arrows,calc,positioning,shadows.blur}

\begin{tikzpicture}[var/.style={draw,circle,inner sep=0pt,minimum size=1.2cm},
  latentconf/.style={draw,circle,dashed,inner sep=0pt,minimum size=1.2cm, fill=green!5}
]
  % Nodes
    \node (A) [var] {$A$};
    \node (Y) [var, right=2.2cm of A] {$Y$};
    \node (U1) [latentconf, above=.8cm of A] {$U_1$};
    \node (X) [var, below right=.2cm and .8cm of U1] {$X$};
    \node (U2) [latentconf, above=.8cm of Y] {$U_2$};
    
    % Arrows
    \path[->, line width=0.5mm]
%        (A) edge (Y)
        (U1) edge (A)
        (U1) edge (X)
        (U2) edge (X)
        (U2) edge (Y);
        
\end{tikzpicture}

\end{document}