View guestbook telemetry data -> Service Graph
Establish port forwarding from local port 8088 to the Service Graph instance:
kubectl -n istio-system port-forward $(kubectl -n istio-system get pod -l app=servicegraph -o jsonpath='{.items[0].metadata.name}') 8088:8088
error: error executing jsonpath "{.items[0].metadata.name}": array index out of bounds: index 0, length 0
Error from server (NotFound): pods "Error executing template: array index out of bounds: index 0, length 0. Printing more information for debugging the template:" not found

As you can see above, istio-1.1.0-rc.5 does not even have Service Graph included. Please update course material.