A propos the Hollar sketches/paintings, I don't think the garrison was particularly well supplied for long periods of its occupation, so uniforms - especially officers' kit - may have been expected to last a while, and the informal stuff, such as the grey coats may even have been designed with longevity in mind. I have often wondered if the men actually fought in their shirtsleeves and coloured waistcoats due to the heat, rather than the full regimental coat. Or maybe they just took the waistcoats off, as the coat would probably give greater protection against edged weapons?
I'm not sure when it dates from (possibly the later period - late 1670s/early 1680s), but there is also a very detailed painting of a massive parade involving the whole of the garrison, which includes naval units, the Duke of York & Albany's Regiment in their yellow coats, and various cavalry troops.
Edit: I think it's called "Lord Dartmouth's parade of the army at Tangier, 1683" and was done just prior to the final evacuation; the troops included a composite Guards battalion (King's and Coldstream), plus detachments of Dumbarton's (later 1st Foot), the 1st Tangier Regiment (later 2nd Foot) which had formed the original garrison, the Buffs (later 3rd Foot), and the newly-raised 2nd Tangier Regiment (later 4th Foot), and the Duke of York's (disbanded in 1690, but widely accepted as the forerunners of the Royal Marines).