Grounding a 3 switch metal device box
Everyone seems to be answering a question that was not asked by the OP.  He is asking if using the bonding screws without also pigtailing the bonding conductors will suffice for bonding.

Yes, the picture you have shown is an appropriate way to bond the devices.

Edit:  Additionally, there is no requirement to bond the switches in the CEC with a separate bonding conductor, unless doing so is stated in the manufacturer's instructions.  The screws used to mount the switch to the box suffice as the bond.