code: function(r, n) {
    /* the Raphael set is obligatory, containing all you want to display */
    var set = r.set().push(
      /* custom objects go here */
      r.rect(n.point[0]-30, n.point[1]-13, 50, 50)
      .attr({"fill": "#fa8", "stroke-width": 2, r: 9}))
      .push(r.text(n.point[0], n.point[1] + 15, n.id)
            .attr({"font-size":"20px"}));
            return set;
  }
docs: Custom render function, to be used as the default for every node