The diagram is using ground symbols, which should never be there!
All ground wires
should must be connected to a single [ground-summing] point, usually on the volume potmeter chassis.
Solder a grounding wire from the tone potmeter chassis to the volume potmeter chassis.
From the volume potmeter, run a shielded cable to the jack socket.
Apart from this, the electronics cavity should be shielded, which should be connected to the volume pot chassis.
Do note that running a grounding wire from the tone potmeter and the switch chassis to volume potmeter [common ground summing point], can create a ground-loop if the potmeters are mounted onto cavity shielding.
In this case, it may be better to rely on the grounding of tone and switch chassis taking place through the cavity shielding The same grounding/shielding precaution applies to the jack socket: All cheap ones have non-isolating all-metal chassis.
Having such a socket mounted onto cavity shielding + running a shielded wire from vol potmeter to the socket almost certainly will create a ground-loop. Better use an isolated jack socket - and a shielded wire
Great pickup wire color code chart, Kim