\documentclass{article}

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\usepackage[T1]{fontenc}
\usepackage{amsmath,amsfonts,amssymb,amsthm}
\usepackage{xcolor}

\definecolor{darkgreen}{rgb}{0.0, 0.45, 0.0}
\definecolor{darkblue}{rgb}{0.0, 0.0, 0.8}

\begin{document}

Matrix for Exercise 3.1:

\begin{center}
	\begin{tabular}{l||ccc|ccc}
		& & \color{darkblue}Zeil & & & \color{darkblue}Eintracht &\\
		\hline\hline
		& & & \color{darkblue}1 &  &  & \color{darkblue}6 \\
		\color{darkgreen}Zeil &  &  &  &  &  &\\
		& \color{darkgreen}2 &  &  & \color{darkgreen}6 & & \\
		\hline     
		& & & \color{darkblue}5 & & & \color{darkblue}2 \\
		\color{darkgreen}Eintracht &  &  &  &  &  &\\
		& \color{darkgreen}5 & & & \color{darkgreen}1 & &\\
	\end{tabular}
\end{center} 

\end{document}