Thank you for contacting Syncfusion support.
We can format the cell using cell template option, kindly visit the below links to know more about the feature. We have prepared the sample to customize the particular resource cell color which can be viewed from the below link.
Kindly refer the below code example used in the sample.
<Code>
workCellsTemplateId: "#workTemplate"
<script id="workTemplate" type="text/x-jsrender">
{{if resource.classname == 'e-parentnode' && view == 'month' && resource.text == "ROOM2" && (date.getDate() == 5 ||date.getDate() == 6||date.getDate() == 7||date.getDate() == 8||date.getDate() == 9)}}
<div style='background-color:#c8c8c8;height:100%'></div>
{{/if}}
{{if view == 'month' && resource.groupId == 2 && (date.getDate() == 5 ||date.getDate() == 6||date.getDate() == 7||date.getDate() == 8||date.getDate() == 9)}}
<div style='background-color:#c8c8c8;height:100%'></div>
{{/if}}
</script>
</Code>
Regards,
Karthigeyan