The easiest method I am aware of is to double click on a sensor.
There should be an option for setting the sensor version.
You should be able to see a list of versions for this field.
Look through the list and find the highest S level.
The highest S level in the list will correspond to the installed signature update on CSPM.
The highest one to date is S11 the sensor version is 3.0(2)S11.