you could build a form with that basic root search and create three different panels charts subsearches or a saved search.
Since 'chart' represents on container and panel, I think you'd need to specific a search for it..
http://docs.splunk.com/Documentation/Splunk/6.0/Viz/PanelreferenceforSimplifiedXML
But since you're working in XML, it's relatively easy to just copy and modify the same container..
You can try searchTemplate and searchPostProcess modules of simple xml as follow:-
<form>
<label>PostProcess Example</label>
<!-- Search that returns all of the data that requested by subsequent panels -->
<searchTemplate>
search logs | ... |...
</searchTemplate>
<row>
<chart>
<title>Count of A over time</title>
<searchPostProcess>timechart count(eval(X="a"))</searchPostProcess>
<option name="height">300px</option>
<option name="charting.chart">area</option>
<option name="charting.chart.stackMode">stacked</option>
</chart>
</row>
<row>
<chart>
<title>Count of B over time</title>
<searchPostProcess>timechart count(eval(X="b"))</searchPostProcess>
<option name="height">300px</option>
<option name="charting.chart">area</option>
<option name="charting.chart.stackMode">stacked</option>
</chart>
</row>
<row>
<chart>
<title>Count of C over time</title>
<searchPostProcess>timechart count(eval(X="c"))</searchPostProcess>
<option name="height">300px</option>
<option name="charting.chart">area</option>
<option name="charting.chart.stackMode">stacked</option>
</chart>
</row>
</form>