\documentclass[varwidth]{standalone}
\usepackage{longtable}
\usepackage[dvipsnames,svgnames,table]{xcolor}
\usepackage{diagbox}
\begin{document}
\rowcolors{2}{lightgray!30}{white}
\begin{longtable}{c|l|l|}
\diagbox[]{slot}{agent}&1&2\\
\hline
\endhead
\hline
\endfoot
1&{\ensuremath{\mathtt{e',e_{1}}}}&{\ensuremath{\mathtt{g',g_{1}}}}\\
2&{\ensuremath{\mathtt{e_{2}}}}&{\ensuremath{\mathtt{f',f_{1}}}}\\
3&{\ensuremath{\mathtt{e_{3}}}}&{\ensuremath{\mathtt{d',d_{1}}}}\\
4&{\ensuremath{\mathtt{b',b_{1}}}}&{\ensuremath{\mathtt{c',c_{1}}}}\\
5&{\ensuremath{\mathtt{a',a_{1}}}}&{\ensuremath{\mathtt{}}}\\

\end{longtable}
\end{document}