In the UK all airways were redesignated several years back to comply with Intl standards, hence loss of all the pretty colours...
It was, allegedly, confusing to a foreign pilot. So they can learn such words as altitude, pressure, procedure, acceleration etc etc etc... but blue, red and white was too difficult for them (I suppose they're only aircrew?)
Not sure where the reference for the standard is... but I was once told he origin of the colours came from the first commercial routes laid out in the US, which were marked by coloured lights... you simply follow the blue route, turn left down the red route and follow it to destination... that's the way to Amarillo?