设置列的颜色在谷歌图表

我正在使用谷歌图表建立一个折线图。我使用类别过滤器来切换显示的列，如下面的小提琴所示。

如何为每个列设置颜色，使它们始终具有该颜色?例如，如果您在小提琴示例中删除列Foo，列Bar将获得其颜色。

google.load('visualization', '1', {packages: ['controls']});
google.setOnLoadCallback(drawChart);
function drawChart () {
    var data = new google.visualization.DataTable();
    data.addColumn('string', 'Year');
    data.addColumn('number', 'Foo');
    data.addColumn('number', 'Bar');
    data.addColumn('number', 'Baz');
    data.addColumn('number', 'Cad');
    data.addRows([
        ['2005',  45, 60, 89, 100],
        ['2006',  155, 50, 79, 24],
        ['2007',  35, 31, 140, 53],
        ['2008',  105, 23, 43, 82],
        ['2009',  120, 56, 21, 67],
        ['2010',  65, 19, 34, 134],
        ['2011',  80, 23, 130, 40],
        ['2012',  70, 140, 83, 90]
    ]);
    var columnsTable = new google.visualization.DataTable();
    columnsTable.addColumn('number', 'colIndex');
    columnsTable.addColumn('string', 'colLabel');
    var initState= {selectedValues: []};
    // put the columns into this data table (skip column 0)
    for (var i = 1; i < data.getNumberOfColumns(); i++) {
        columnsTable.addRow([i, data.getColumnLabel(i)]);
        // you can comment out this next line if you want to have a default selection other than the whole list
        initState.selectedValues.push(data.getColumnLabel(i));
    }
    // you can set individual columns to be the default columns (instead of populating via the loop above) like this:
    // initState.selectedValues.push(data.getColumnLabel(4));
    var chart = new google.visualization.ChartWrapper({
        chartType: 'BarChart',
        containerId: 'chart_div',
        dataTable: data,
        options: {
            title: 'Foobar',
            width: 600,
            height: 400
        }
    });
    var columnFilter = new google.visualization.ControlWrapper({
        controlType: 'CategoryFilter',
        containerId: 'colFilter_div',
        dataTable: columnsTable,
        options: {
            filterColumnLabel: 'colLabel',
            ui: {
                label: 'Columns',
                allowTyping: false,
                allowMultiple: true,
                allowNone: false,
                selectedValuesLayout: 'belowStacked'
            }
        },
        state: initState
    });
    function setChartView () {
        var state = columnFilter.getState();
        var row;
        var view = {
            columns: [0]
        };
        for (var i = 0; i < state.selectedValues.length; i++) {
            row = columnsTable.getFilteredRows([{column: 1, value: state.selectedValues[i]}])[0];
            view.columns.push(columnsTable.getValue(row, 0));
        }
        // sort the indices into their original order
        view.columns.sort(function (a, b) {
            return (a - b);
        });
        chart.setView(view);
        chart.draw();
    }
    google.visualization.events.addListener(columnFilter, 'statechange', setChartView);
    setChartView();
    columnFilter.draw();
}