File:DirectProductofTriangles.svg

\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\newcommand\red{\draw[thick,red,double]}
\newcommand\blue{\draw[thick,blue]}
\path(-1.8,-1)rectangle(6,6.8);
\begin{scope}[inner sep=0.5mm]
  \red(-0.4,6)--(0,6)node[circle,fill,black](K0){};
  \red(-1,-0.4)--(-1,0)node[circle,fill,black](L0){};
  \foreach \n/\m/\o in {0/1/2,2/3/4}{
    \blue(K\n)--(\m,6)node[circle,fill,black](K\m){};
    \red(K\m)--(\o,6)node[circle,fill,black](K\o){};
    \blue(L\n)--(-1,\m)node[circle,fill,black](L\m){};
    \red(L\m)--(-1,\o)node[circle,fill,black](L\o){};
  }
  \blue(K4)--(5,6)node[circle,fill,black](K5){};
  \red(K5)--(5.4,6){};
  \blue(L4)--(-1,5)node[circle,fill,black](L5){};
  \red(L5)--(-1,5.4){};
  \draw[thick,gray,dashed](-1.3,5.4)--(-0.7,5.4);
  \draw[thick,gray,dashed](-1.3,-0.4)--(-0.7,-0.4);
  \draw[thick,gray,dashed](5.4,6.3)--(5.4,5.7);
  \draw[thick,gray,dashed](-0.4,6.3)--(-0.4,5.7);
\end{scope}
\begin{scope}
\clip(-0.4,-0.4)rectangle(5.4,5.4);
\foreach \n in {0,1,2,3,4,5}{
  \foreach \m in {0,1,2,3,4,5}{
    \node[fill,circle,inner sep=0.5mm](V\n\m)at(\n,\m){};
  }
}
\foreach \nx/\ny in {0/1,2/3,4/5}{
  \foreach \mx/\my in {0/1,2/3,4/5}{
    \blue(V\nx\mx)--(V\ny\my);
    \blue(V\nx\my)--(V\ny\mx);
  }
}
\foreach \nx/\ny in {1/2,3/4}{
  \foreach \mx/\my in {1/2,3/4}{
    \red(V\nx\mx)--(V\ny\my);
    \red(V\nx\my)--(V\ny\mx);
  }
}
\foreach \n in {0,2,4}{
  \foreach \m/\o in {0/-0.5,5/0.5}{
    \red(V\m\n)--(\m+\o,\n-0.5);
    \red(V\n\m)--(\n-0.5,\m+\o);
  }
}
\foreach \n in {1,3}{
  \foreach \m/\o in {0/-0.5,5/0.5}{
    \red(V\m\n)--(\m+\o,\n+0.5);
    \red(V\n\m)--(\n+0.5,\m+\o);
  }
}
\red(V55)--(5.4,5.4);
\end{scope}
\draw[thick,gray,dashed](-0.4,-0.4)rectangle(5.4,5.4);
\end{tikzpicture}
\end{document}