图例中的Chart js嵌套饼图标签颜色

  var ctx = $("#myChart");
  var myChart = new Chart(ctx, {
    type: 'pie',
    data: {
      labels: ['InnerLabel1','InnerLabebl2','InnerLabel3'],
      datasets: [{
        data: [1, 2, 1, 4],
        backgroundColor: [
          'rgba(31,119,180,0.5)','rgba(255,127,14,0.5)','rgba(255,127,14,0.5)','rgba(44,160,44,0.5)'
        ],
        labels: [
          'OuterLabel1','OuterLabel2','OuterLabel3','OuterLabel4'
        ]
      }, {
        data: [1, 3, 4],
        backgroundColor: [
          '#1f77b4','#ff7f0e','#2ca02c'
        ],
        labels: ['InnerLabel1','InnerLabebl2','InnerLabel3'],
      }, ]
    },
    options: {
      responsive: true,
      legend: {
        display: true,
      },
      tooltips: {
        callbacks: {
            label: function(tooltipItem, data) {
            var dataset = data.datasets[tooltipItem.datasetIndex];
            var index = tooltipItem.index;
            return dataset.labels[index] + ': ' + dataset.data[index];
          }
        }
      }
    }
  });

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.5.0/Chart.js"></script>
<canvas id="myChart"></canvas>