Its very difficult to find any info about uniform colours, I was talking to a couple of guys at the L&L and they thought that as the method of decking out their retinue troops in livery colours in England was so taken for granted there was no reason to suppose that the practice was not carried out up North by the Scots nobles, who also had (in some cases) quite large well armed retinues troops.
I don't think that any but the retinue or noble troops would be so issued, the majority of the Common militia would be homespun wool tunics.
The reason I was thinking that maybe the town/city militias could have some sort of uniform was that it was not unknown on the continent and in England that some towns/cities did issue some sort of uniform to their levied troops, so maybe the practise was carried out in some fashion in Scotland.
Anyway I think that a lot of the info available on Scots uniforms (in this particular period) is quite conjectural, so feel quite happy to paint my figs with a wee bit more colour.