\begin{tikzpicture}[->,>=stealth,shorten >=1pt,auto,scale=0.6,transform shape]
	% x node set with absolute coordinates
	\node[state] (C1) at (-1.5,1.5) {$C_1$};
	\node[state] (C2) at (-1.5,-1.5) {$C_2$};
	\node[dstate] (X1) at (0,0) {$X_1$};
	\node[dstate] (Y1) at (1.5,1.5) {$Y_1$};
	\node[dstate] (Z1) at (1.5,-1.5) {$Z_1$};
	\node[dstate] (X2) at (3,0) {$X_2$};
	\node[dstate] (Y2) at (4.5,1.5) {$Y_2$};
	\node[dstate] (Z2) at (4.5,-1.5) {$Z_2$};
	\node[dstate] (X3) at (6,0) {$X_3$};
	\node[dstate] (Xn) at (9,0) {$X_n$};
	\node[dstate] (Yn) at (10.5,1.5) {$Y_n$};
	\node[dstate] (Zn) at (10.5,-1.5) {$Z_n$};
	\node at ($(X3)!.5!(Xn)$) {\ldots};
	% Directed edge
	\path (X1) edge (C1);
	\path (X1) edge (C2);
	\path (Y1) edge (X1);
	\path (Z1) edge (X1);
	\path (X2) edge (Y1);
	\path (X2) edge (Z1);
	\path (Y2) edge (X2);
	\path (Z2) edge (X2);	
	\path (X3) edge (Y2);
	\path (X3) edge (Z2);
	\path (Yn) edge (Xn);
	\path (Zn) edge (Xn);
	% Bidirected edge
	%\path[bidirected] (A) edge[bend left=60] (C);
	%\node at ($(1)!.5!(2)$) {\ldots};
\end{tikzpicture}