I've done something like what you're trying to do
You'll need to create some super metrics and views for this.
Super Metric
Total Active Storage usage
sum(Virtual Machine: Guest File System|Utilization) This needs to be the sum of Total Disk Usage for all VMs in custom group.
Total Active Memory Usage
sum of group memory util
Total Active CPU Usage
sum of group CPU demand
This requires 3 widgets due to the 3 views.
Your view will need to use the Distribution under Presentation with the Pie Chart visualization selected.
Subjects tab: <custom group> containing our specific VMs.
Data tab: Select data for <subject tab info>
Metric: Select your super metric (mem,CPU,storage)
Using the View (Pie) widget.
Config tab:
refresh content set to On, Refresh Interval is 300 seconds, Self Provider set to On.
Input Data tab:
Inventory trees : All Objects
Object: <custom group name>
Object Type: Environment
Output Data tab:
Select <custom view> one for each CPU, Mem, Disk util