\begin{tikzpicture}[
    squarednode/.style={rectangle, draw=black!20, fill=white!5, very thick, minimum size=1cm},
    ]
    
    \node[squarednode] at (0.5,0.5) (int) {1};
    \node[squarednode] at (1.5,0.5) (int) {2};
    \node[squarednode] at (2.5,0.5) (int) {4};
    \node[squarednode] at (3.5,0.5) (int) {7};
    \node[squarednode] at (0.5,1.5) (int) {3};
    \node[squarednode] at (1.5,1.5) (int) {5};
    \node[squarednode] at (2.5,1.5) (int) {8};
    \node[squarednode] at (0.5,2.5) (int) {6};
    \draw[] (0,0)--(4,0)--(4,1)--(3,1)--(3,2)--(1,2)--(1,3)--(0,3)--cycle;
\end{tikzpicture}