This page shows all the pads that contain electronics, clearances, etc. The surface mount stuff is all MUCH shorter than the various connectors.
Also, at the very bottom of that page is a link to github. The T3P3/SmartEffector/SmartEffector_v2.0/SmartEffector.kicad_pcb file is literally the board file that can be loaded in KiCAD so you can see the PCB layout. I don't use KiCAD, and therefore don't have it installed, or I would screen shot it for you.
The strain gauge itself is a set of very fine traces in the circuit board etch. They form a "tri-spiral" around the center.
You can actually see the traces that form the strain gauge in this photo (also linked from that same page).