レポート実行結果のグラフではないのですが、<apex:chart>というタグでグラフの

表示が可能みたいです。

この方法はいかがでしょうか。

■Apexクラス・サンプル

public class ChartController {
    // Return a list of data points for a chart 
    
    public List<Data> getData() {
        return ChartController.getChartData();
    }
    
    // Make the chart data available via JavaScript remoting 
    
    @RemoteAction
    public static List<Data> getRemoteData() {
        return ChartController.getChartData();
    }

    // The actual chart data; needs to be static to be 
    
    // called by a @RemoteAction method 
    
    public static List<Data> getChartData() {
        List<Data> data = new List<Data>();
        data.add(new Data('Jan', 30, 90, 55));
        data.add(new Data('Feb', 44, 15, 65));
        data.add(new Data('Mar', 25, 32, 75));
        data.add(new Data('Apr', 74, 28, 85));
        data.add(new Data('May', 65, 51, 95));
        data.add(new Data('Jun', 33, 45, 99));
        data.add(new Data('Jul', 92, 82, 30));
        data.add(new Data('Aug', 87, 73, 45));
        data.add(new Data('Sep', 34, 65, 55));
        data.add(new Data('Oct', 78, 66, 56));
        data.add(new Data('Nov', 80, 67, 53));
        data.add(new Data('Dec', 17, 70, 70));
        return data;
    }
    
    // Wrapper class 
    
    public class Data {
        public String name { get; set; }
        public Integer data1 { get; set; }
        public Integer data2 { get; set; }
        public Integer data3 { get; set; }
        public Data(String name, Integer data1, Integer data2, Integer data3) {
            this.name = name;
            this.data1 = data1;
            this.data2 = data2;
            this.data3 = data3;
        }
    }
}

■Apexページ・サンプル①：円グラフ

<apex:page controller="ChartController">
    <apex:chart data="{!data}" height="300" width="400" background="#F5F5F5">
        <apex:legend position="left"/>
        <apex:pieSeries labelField="name" dataField="data1"  colorSet="#37241E,#94B3C8,#4D4E24,#BD8025,#816A4A,#F0E68C"/>
    </apex:chart>
</apex:page>

■Apexページ・サンプル②：棒グラフ

<apex:page controller="ChartController">
    <apex:chart data="{!data}" height="400" width="500">
    <apex:legend position="left"/>
    <apex:axis type="Numeric" position="left" title="Closed Won" grid="true"  fields="data1,data2,data3" dashSize="2">
        <apex:chartLabel />
    </apex:axis>
    <apex:axis type="Category" position="bottom" fields="name" title="Stacked Bars">
        <apex:chartLabel rotate="315"/>
    </apex:axis>
    <apex:barSeries orientation="vertical" axis="left" stacked="true"  xField="name" yField="data1,data2,data3" title="MacDonald,Promas,Worle"/>
</apex:chart>
</apex:page>