\documentclass{article}
\usepackage[pdftex,active,tightpage]{preview}
\setlength\PreviewBorder{2mm}

\usepackage{tikz}
\usetikzlibrary{arrows,positioning}
\pgfdeclareimage{user}{user}
\pgfdeclareimage{schwarz}{user-schwarz}
\pgfdeclareimage{rot}{user-rot}

\begin{document}
\begin{preview}
\begin{tikzpicture}[scale=2]
    \node[text width=2.2cm,align=center] (a) at (0,1) {\pgfuseimage{user}\newline Anna};
    \node[text width=2.2cm,align=center] (b) at (5,1) {\pgfuseimage{schwarz}\newline Berta};
    \node[text width=2.2cm,align=center] (c) at (8,0) {\pgfuseimage{rot}\newline Charlie};
    \node[text width=2.2cm,align=center] (d) at (9,2) {\pgfuseimage{user}\newline Doris};
    \node[text width=2.2cm,align=center] (e) at (4,3) {\pgfuseimage{schwarz}\newline Erich};
    \node[text width=2.2cm,align=center] (f) at (6,3) {\pgfuseimage{rot}\newline Fritz};
    \node[text width=2.2cm,align=center] (g) at (7,4) {\pgfuseimage{user}\newline Gerd};

    \draw (a) -- (b);
    \draw (a) -- (e);
    \draw (b) -- (e);
    \draw (b) -- (f);
    \draw (b) -- (c);
    \draw (c) -- (d);
    \draw (e) -- (f);
    \draw (e) -- (g);
    \draw (f) -- (g);
\end{tikzpicture}
\end{preview}
\end{document}