British troops all blue.
Scottish troops red/white diced band?For British troops the colour of Kilmarnock would depend on the branch of service. Light Infantry and rifles would have worn dark green caps. Whether the colour was invisible beneath a white cover would depend on the regiment.
Undress bonnets in Highland corps depended on the regiment.
The 42nd had plain Kilmarnock bonnets, although I have yet to see conclusive evidence as to what they wore in India during the Mutiny. In the 1890s Harry Payne painted a well known image of Black Watch soldiers in India wearing Kilmarnocks with white covers and peaks but that does not mean a great deal.
Technically speaking, all kilted regiments should have been wearing glengarry bonnets for undress headgear since 1851; the 79th Cameron Highlanders wearing the plain bonnets they had worn since the 1840s; the 78th and 93rd with band of dicing, the latter with red-and-white Sutherland chequer pattern.
There are however indications that the 78th, having become separated from their feather bonnets, were wearing Kilmarnocks for campaigning in India, which were easier to fit with sun covers and neck shades. They also wore more arcane forms of headgear unique to the Mutiny campaigns (see links below). We only see images of the 79th and 93rd wearing feather bonnets fitted up with quilted sunshades. Presumably they had undress bonnets tucked away somewhere but there is no evidence I am aware of to confirm what form they took. We know that by the 1860s, the 93rd in India were once again Kilmarnocks instead of the Glengarry, but that doesn't necessarily mean they had re-adopted them during the Mutiny. I think it is fair to say, however, you will be hard put to find a contemporary, reliable image of a Glengarry bonnet from the Mutiny period.
The 72nd as a non-kilted Highland regiment would have wore a standard Kilmarnock with diced band with the option of a cover.
I am writing this from memory, and I should be asleep but I hope that general outline will serve. Mike Snook might chip in if he has a moment.
Meanwhile these threads may prove interesting regarding Kilmarnocks and Highland undress bonnets. You'll need to scroll through a bit to find posts directly relevant to India, but it's all interesting stuff.viewtopic.php?f=11&t=2356viewtopic.php?f=19&t=7898&hilit=bonnetviewtopic.php?f=19&t=6050&hilit=+bonnet