While that can by all means be the cause, I think the jet fuel exhausted residue contains imperfections which, when under light, will shine and reflect colour (much like when the sun reflects off an oil puddle) . The evidence for this claim is the sporadic and mixed look of the colours which matches the oil reflection. Rainbows, no matter how mixed, are always in their colour pattern.
What's more, the planes surface should be hot, not cold. Even though temperatures are low at that altitude, the friction of the air against the plane would cause it to heat up (which is why it needs to be cooled down).
friction with the air probably does not effect the temp of the plain as much as you would think, the underside of the plain is likely getting hot due to a effect called aerodynamic heating. the top of the plain is likely getting cold due to a revers effect caused by a partial vacuum.
Don't you mean sonic rainboom? After seeing this picture on funsubstance a while back, I worked out the physics of rainbow dash's sonic rainboom. Turns out it is possible, but very unlikely, for a human to do a sonic rainbom.
SONIC rainbow
And rainbow is gay
It joke
:/