\documentclass{article}
\usepackage{threeparttable}
\usepackage{multirow}
\usepackage{booktabs}
\usepackage{xcolor}
\begin{document}
\begin{table}[!ht]
\setlength\tabcolsep{0pt}
\centering
\begin{threeparttable}
\begin{tabular}{@{\extracolsep{2ex}}*{5}{lcccc}}
\toprule
 & \multicolumn{4}{c}{\textbf{group2}} \\
\cmidrule{2-5}
 & \multicolumn{2}{c}{e} & \multicolumn{2}{c}{f} \\
 & \multicolumn{2}{c}{\textbf{group3}} & \multicolumn{2}{c}{\textbf{group3}} \\
\cmidrule{2-3}\cmidrule{4-5}
 & c & d & c & d \\
\textbf{group1} & \multicolumn{4}{c}{\textbf{value1}} \\
\midrule
a & 1 & 3 & 2 & 4 \\
b & 5 & 7 & 6 & 8 \\
\bottomrule
\end{tabular}
\end{threeparttable}
\end{table}
\end{document}