It's not quite true that the color scheme doesn't matter.
Each of those
twisted pairs can be thought of as carrying a
signal in one direction and its
return
(you can think of it as the
ground wire)
in the other direction.
For the
ethernet to work as designed
(and
especially if you're going to be using it as
100BaseT) it's vital that each signal and its return be part of the same twisted pair.
Once upon a time, ethernet used fancy coaxial cable, since coaxial cable has much better propagation properties for electric fields than plain wires do.
It turns out that twisted pairs are better at propagating fields than plain wires, too, and eventually someone figured out how to run ethernet over them instead, which was a boon, because twisted pair wiring is much cheaper and easier to install than coax.
So, no, it doesn't matter where the orange, blue, green, and brown go per se,
but pins 1 and 2 must be a twisted pair, and pins 3 and 6 must be a twisted pair, and pins 4 and 5 must be a twisted pair, and finally pins 7 and 8 must be a twisted pair.
It's kind of a strange pattern, but there's a bit of a method to it.
For one thing, the middle 4 pins (3, 4, 5, and 6) end up being wired just like a standard RJ-14 two-line phone jack,
so you can easily run phone signals through your network wiring if you have to.
If you screw the wiring up, for example if you make pins 3 and 4 be the green pair, and 5 and 6 be the blue pair (which is an easy mistake to make), it might work for 10BaseT, but you're skating on vanishingly thin ice / pushing outside the envelope / etc.