
\tikzset{
  group/.append style={
    align=center,
    text=black,
    scale=1.0
  },
  cell/.append style={
    draw, fill=gray!30!white, rounded corners
  }
}



\begin{tikzpicture}

%C1
\node [cell, minimum width=3cm, minimum height=5cm, label=$C_1$] at (0,0) {};

\draw[fill=gray!60!white] (-0.75, 2) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X1) {$\mathbf{X_1}$};
\draw[fill=gray!60!white] (+0.75, 2) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X2) {$\mathbf{X_2}$};
\draw[fill=gray!60!white] (-0.75, 1) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X3) {$\mathbf{X_3}$};
\draw[fill=gray!60!white] (+0.75, 1) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X4) {$\mathbf{X_4}$};
\draw[fill=gray!60!white] (-0.75, 0) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X5) {$\mathbf{X_5}$};
\draw[fill=gray!60!white] (+0.75, 0) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X6) {$\mathbf{X_6}$};
\draw[fill=gray!60!white] (-0.75, -1) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X7) {$\mathbf{X_7}$};
\draw[fill=gray!60!white] (+0.75, -1) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X8) {$\mathbf{X_8}$};
\draw[fill=gray!60!white] (-0.75, -2) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X9) {$\mathbf{X_9}$};
\draw[fill=gray!60!white] (+0.75, -2) ellipse (0.6cm and 0.3cm) coordinate node [group] (C1_X10) {$\mathbf{X_{10}}$};



\node [cell, minimum width=1.5cm, minimum height=1cm, label=$C_2$] at (2.5,0) {};
\draw[fill=gray!60!white] (2.5, 0) ellipse (0.6cm and 0.3cm) coordinate node [group] (C2_X1) {$\mathbf{X_1}$};


\node [cell, minimum width=1.5cm, minimum height=3cm, label=$C_3$] at (4.25,0) {};
\draw[fill=gray!60!white] (4.25, 1) ellipse (0.6cm and 0.3cm) coordinate node [group] (C3_X1) {$\mathbf{X_1}$};
\draw[fill=gray!60!white] (4.25, 0) ellipse (0.6cm and 0.3cm) coordinate node [group] (C3_X2) {$\mathbf{X_2}$};
\draw[fill=gray!60!white] (4.25, -1) ellipse (0.6cm and 0.3cm) coordinate node [group] (C3_X3) {$\mathbf{X_3}$};


\node [cell, minimum width=1.5cm, minimum height=2cm, label=$C_4$] at (6,0) {};
\draw[fill=gray!60!white] (6, 0.5) ellipse (0.6cm and 0.3cm) coordinate node [group] (C4_X1) {$\mathbf{X_1}$};
\draw[fill=gray!60!white] (6, -0.5) ellipse (0.6cm and 0.3cm) coordinate node [group] (C4_X2) {$\mathbf{X_2}$};


\node [cell, minimum width=1.5cm, minimum height=2cm, label=$C_5$] at (7.75,0) {};
\draw[fill=gray!60!white] (7.75, 0.5) ellipse (0.6cm and 0.3cm) coordinate node [group] (C5_X1) {$\mathbf{X_1}$};
\draw[fill=gray!60!white] (7.75, -0.5) ellipse (0.6cm and 0.3cm) coordinate node [group] (C5_X2) {$\mathbf{X_2}$};

\node [cell, minimum width=1.5cm, minimum height=1cm, label=$C_6$] at (9.5,0) {};
\draw[fill=gray!60!white] (9.5, 0) ellipse (0.6cm and 0.3cm) coordinate node [group] (C6_X1) {$\mathbf{X_1}$};


\draw[-latex, black, very thick] (C1_X4) to[bend left=20] (C1_X5);
\draw[-latex, black, very thick] (C1_X6) to[bend right=50] (C1_X10);
\draw[-latex, black, very thick] (C1_X9) to[bend left=10] (C1_X7);

\draw[-latex, black, very thick] (C2_X1) to[bend right=75] (C6_X1);


\draw[-latex, black, very thick] (C3_X2) to[bend left=10] (C3_X1);
\draw[-latex, black, very thick] (C3_X2) to[bend right=10] (C3_X3);


\draw[-latex, black, very thick] (C4_X2) to[bend left=10] (C4_X1);

\draw[-latex, black, very thick, dotted] (C5_X2) to[bend left=10] (C4_X1);







\end{tikzpicture}
