\documentclass{minimal}

% Tikz
\usepackage{pgf}
\usepackage{tikz}
\usepackage{color}

\definecolor{ACG}{RGB}{55,91,64}

\begin{document}

\begin{center}

%\colorbox{ACG}{

\begin{tikzpicture}
 [
 	vertex/.style={draw=none,circle,fill=white,minimum size=2pt},
	edge/.style={draw,white,thick},
	redge/.style={line width=3pt,color=red!50!white}
 ]

\begin{scope}[xshift=-5cm]

\coordinate (V1) at (-3,3);
\coordinate (V2) at (0,0);
\coordinate (V3) at (0,6);
\coordinate (V4) at (3,3);

\draw[edge] (V1) to (V2) {};

\draw[edge] (V1) -- (V3) {};

\draw[redge] (V1) -- (V4) {};

\draw[edge] (V2) -- (V4) {};

\draw[edge] (V3) -- (V4) {};

\node[vertex] at (V1) {};
\node[vertex] at (V2) {};
\node[vertex] at (V3) {};
\node[vertex] at (V4) {};

\end{scope}

\draw[->,>=latex,thick,white] (-1.5, 4) arc (105:75:6);
\node[above] at (0, 4.2) {\textcolor{white}{\textbf{Flip edge}}};

\begin{scope}[xshift=5cm]

\coordinate (V1) at (-3,3);
\coordinate (V2) at (0,0);
\coordinate (V3) at (0,6);
\coordinate (V4) at (3,3);

\draw[edge] (V1) to (V2) {};

\draw[edge] (V1) -- (V3) {};

\draw[redge] (V2) -- (V3) {};

\draw[edge] (V2) -- (V4) {};

\draw[edge] (V3) -- (V4) {};

\node[vertex] at (V1) {};
\node[vertex] at (V2) {};
\node[vertex] at (V3) {};
\node[vertex] at (V4) {};

\end{scope}
\end{tikzpicture}

%}

\end{center}

\end{document}