The output from a guitar pickup has bugger all to do with data rates/speeds and the like. Those figures are all to do with digital data, a guitar outputs an analogue signal.
Basically pickups generate a varying voltage, which your amp turns into sound.
You need two wires between guitar and amp, one for signal one for ground.
To avoid interferance from external electromagnetic fields it's best to use a shielded cable for this.
Basically a shielded cable has a metal mesh outer shield around the inner core. This shield is often used for the ground. This outer mesh does it's best to absorb any interferance and try to lessen the amount that gets through to the core carrying the signal.
By changing what plugs and sockets you use it's not really making any difference to the basic concept.
If you fancy it though you could use XLR leads or stereo TRS jacks to carry a balanced signal down a cable. This would be even more resistant to interferance, although would really only be worth doing if whatever you were plugging your guitar into was capapable of recieving a balanced signal. Which guitar amps ain't but most mixing desks are.
A balanced cable requires 3 wires, one for HOT one for COLD and one for GROUND.
The HOT signal is your normal signal, the COLD carries the normal signal INVERTED, and the ground is the ground.
The sound the signal represents can be pictured as a wave, it you turn this wave upside down, that's the inverted signal. This means that any interferance will be picked up by both the hot and the cold signals, at the other end of the cable the cold signal is then inverted again so it now matches the hot signal.
The clever bit is if any interferance was picked up then it will exist in both signals, but as the cold signal has be re-inverted this means that the interferance on the cold signal is the inverse of the interferance on the hot signal, although the actual wanted signal is no longer inverse. So if you simply add the two signals back together the two lots of interferance cancel each other out and leave you with the original signal minus the interferance.
You want pics?
So you could make a guitar with an XLR socket or stereo jack, which are both capable of carrying the three signals. But like I said, whatever you are plugging into needs to know how to invert the cold back and do the addition.
If you just fancy the idea of something funky on your guitar like an XLR plug then you could just wire a cable so that it used only two of the pins and connected to a jack at the other end that you could plug into any amp. Basically quality mic cable don't differ alot from quality intrument cable.
Cat 5 I wouldn't be up for using for intrument voltages, the seperate cores are a little thin. Great for digital signals though where intererance isn't such an issue with solutions like error correction and the like.
Now if you fancied putting an ADC (Analog to Digital Converter) inside the guitar and then using a cable to carry the digital signal, you could use CAT5, or even optical cable with the right hardware. Of course at the other end again you will need similar systems to plug it into. (Which you don't get on guitar amps!)
The real question is, WHY? Quality 6mm jack instrument cable works fine? If you want a better quality then go balanced, if you just want the funky look of an XLR jack then just wire up a cable with signal and ground and ignore the third pin. This is what cheap XLR mics do