I want to draw a diamond shape commutative diagram using tikz. Instead of just letters I want to have simple graphs (just edges and vertices) in the diagram. I tried some stuff but the diagram still looks superugly. Is there any way to make this look smoother?
\documentclass[a4paper,12pt]{article}
\usepackage{tikz}
\usepackage{tikz-cd}
\usetikzlibrary{matrix,arrows}
\begin{document}
\begin{center}
\begin{tikzcd}
&
\begin{tikzpicture}%B
[every node/.style={circle,fill=black,inner sep=3pt}]
\node (a) at (0,0) {};
\node (b) at (0,-1) {};
\node[olive] (d) at (1,0) {};
\node[olive] (f) at (0,1) {};
\foreach \from/\to in {a/b,a/d,a/f}
\draw (\from) -- (\to);
\end{tikzpicture}
\arrow{dr} &\\
\begin{tikzpicture}%A
[every node/.style={circle,fill=black, inner sep=3pt}]
\node (a) at (0,0.5) {};
\node (b) at (0,-0.5) {};
\foreach \from/\to in {a/b}
\draw (\from) -- (\to);
\end{tikzpicture}
\arrow{ur} \arrow{dr} & &
\begin{tikzpicture}%Amalgam
[every node/.style={circle,fill=black, inner sep=3pt}]
\node (a) at (1,1) {};
\node (b) at (1,0) {};
\node[orange] (c) at (0.125,0.5) {};
\node[olive] (d) at (2,1) {};
\node[orange] (e) at (1.7,1.7) {};
\node[olive] (f) at (1,2) {};
\foreach \from/\to in {a/b, a/c,a/d,a/e,a/f,c/b}
\draw (\from) -- (\to);
\end{tikzpicture}\\
&
\begin{tikzpicture}%C
[every node/.style={circle,fill=black, inner sep=3pt}]
\node (a) at (1,1) {};
\node (b) at (1,0) {};
\node[orange] (c) at (0.125,0.5) {};
\node[orange] (e) at (1.7,1.7) {};
\foreach \from/\to in {a/b,a/c,a/e,c/b}
\draw (\from) -- (\to);
\end{tikzpicture}
\arrow{ur}
&\\
\end{tikzcd}
\end{center}
\end{document}


