LaTeX set table rule color outside table
\documentclass{article}
\usepackage[table]{xcolor}
\begin{document}
\bgroup
\arrayrulecolor{blue!70}
\begin{tabular}{|*6{c|}}\hline
a & b & c & d & e & f\\\hline
a & b & c & d & e & f\\\hline
\end{tabular}
\egroup
\end{document}