legendMarkerColor: String

Sets the color of marker that is displayed on legend. This property overrides default Marker’s Color in Legend, which is same as dataSeries Marker Color. Value of legendMarkerColor can be “HTML Color Name” or “hex code”.

var  chart =  new  CanvasJS.Chart("container",
{
 .
 .
 data:[{
  legendMarkerColor: "red",

 },
 ]
 .
 .
});
chart.render();