I can't give you a definitive answer, but as they were only issued as needed, I would imagine that the '37 style ones were left khaki, as that would suit all environments and dress, as was the case with the webbing itself (it could also be issued to be whitened for 'No. 1 Rig' if needed too).
The later wool puttee/ankle wraps were a 'light navy blue' though; lighter than the trousers, darker than the shirt.
That being said I wouldn't commit to saying they were never khaki... and all of a unit would turned out the same, the Navy are funny like that.
You only need to look at the first page of Part 6 for the shirt/trouser colours, unless you really want to read through it all and be informed on such things as how the cap ribbon is tied and trimmed and how cabin stewards should be turned out etc.
This might help, barring the white belt, it is pretty accurate, not much changed between 1961 and 1980-something, except the rifles...