How to draw a graph in TikZ
We will use a TikZ standalone document. This can then be included in a Beamer document. (TikZ and Beamer do no mesh well. It also saves compile time for slides.)
The following LaTeX code:
\documentclass[12pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage[cm]{sfmath}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tikzpicture}[
x=1.3cm,
y=1.3cm,
cell/.style={circle},
blue cell/.style={cell, fill=cyan!25!white},
gen edge/.style={thick,->,-{Latex[width=2mm]}}]
\node[blue cell] (Z) at (0,0.2) {$Z$};
\node[blue cell] (A) at (-.8,-1) {$A$};
\node[blue cell] (X) at (1,-1) {$X$};
\node[blue cell] (V) at (1,0.2) {$V$};
\draw[gen edge] (Z) edge (A);
\draw[gen edge] (Z) edge (X);
\draw[gen edge] (V) edge (X);
\end{tikzpicture}
\end{document}
generates the following graph:
