\def\n{7}
\def\radius{2cm}

\begin{tikzpicture}
    \foreach \i in {1,...,\n} 
        \node[draw, small vertex] (v-\i) at ({-360/\n * (\i+3)}:\radius) {};
        
        \foreach \u/\v/\color in {1/2/red,2/3/blue,3/4/red,4/5/blue,5/6/red,6/7/blue,7/1/red} 
            \draw[thick, draw=\color] (v-\u) -- (v-\v);
\end{tikzpicture}
