score:2

use this.area not this.graph, see: http://jsfiddle.net/cms5lrdv/23/

                mouseover: function () {
                   var self = this,
                       serie = this.chart.series;
                   $.each(serie, function (i, e) {
                       if(this != self) {
                           this.area.attr({
                               fill:  colors_grey[i],
                               fillcolor: "#ff0000",
                               stroke:  "#ff0000",
                           });
                       } else {
                           this.area.attr({
                               fill:  "orange",
                               fillcolor: "#ff0000",
                               stroke:  "#ff0000",
                           });   
                       }
                    });

                },

Related Query

More Query from same tag