\documentclass[border=1pt]{standalone}
\usepackage[polish]{babel}
\usepackage[utf8]{inputenc} 
\usepackage[T1]{fontenc}
\usepackage{fourier}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}[vertex/.style={minimum size=4mm, fill=gray!30}]
\foreach \i in {1,...,8} 
  \foreach \j in {1,...,8} \node[vertex] at (\i*0.5,\j*0.5) {};
\end{tikzpicture}

\end{document}