How to customize color in pie chart of NVD3

If you want to use specific color for pie

chart.color(function(d){
    return d.data.color
});

Then, organize your data as:

[
  {
    key: "Cumulative Return",
    values: [
      { 
        "label": "One",
        "value" : 29.765957771107,
        "color" : "#8c564b"
      } ,
      { 
        "label": "Three",
        "value" : 32.807804682612,
        "color" : "#e377c2"
      } 
    ]
  }
]