Curved arrows on top of every node

I'm a beginner of latex and tikz. I want to have curved arrows on top of each node as in tikx example.

Following is my code.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}

\begin{figure}[h]
\centering
\begin{tikzpicture}
  [scale=.8,auto=left,every node/.style={circle,fill=blue!20}]


  \node (n1) at (9,8) {1};
  \node (n2) at (6,7) {2};
  \node (n3) at (5,5)  {3};
  \node (n4) at (6,3) {4};
  \node (n5) at (9,2)  {5};
  \node (n6) at (12,3)  {6};
  \node (n7) at (13,5)  {7};
  \node (n8) at (12,7)  {8};


  \foreach \from/\to in {n1/n2,n2/n3,n3/n4,n4/n5,n5/n6,n6/n7,n7/n8,n8/n1,n1/n3,n1/n4,n1/n5,n1/n6,n1/n7,n2/n4,n2/n5,n2/n6,n2/n7,n2/n8,n3/n5,n3/n6,n3/n7,n3/n8,n4/n6,n4/n7,n4/n8,n5/n7,n5/n8,n6/n8}
    \draw (\from) -- (\to);

\end{tikzpicture}
\end{figure}

\end{document}

How to draw curved arrows on top of every node?