Howard Cole's book remains the best overall guide, although in dealing with formation signs in general, it features more cloth patches and these can differ from vehicle use.
With motorcycles of course we come back to the Army Council Instructions dating back to February 1942 (at least) which state that formation signs were not to be carried on motorcycles.
There are other sources which provide more detailed specific information but it would first be necessary to decide upon unit, date and theatre.
Hodges & Taylor provides lots of background information and is the most complete source on Arm of Service serials but does not claim to include all formation signs.
Cole is still my first port of call to identify but further research is needed before marking up a vehicle.
In terms of the BEF of 1939 / 1940 Andrew Foulkes' superbly illustrated 'Vehicle Markings of the BEF (From the GHQ Diary of 11th April 1940)' is unsurpassed but this is of course a fairly narrow interest !