\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{graphs}
\begin{document}
\tikzstyle{first} = []
\tikzstyle{second} = []
\tikzstyle{third} = []
\tikzstyle{fourth} = []
\input{manfreds_labyrinth_graph.tikz}
\end{document}