This topic has always confused me. First, there is a matter of semantics. I don't think there was such a thing as an "orderly" in the French system.
If you mean "adjutant," I have at least one source.
Adjutant Commandant
Black cocked hat, the blue-red-white cockade underlaid with a golden rosette.
All dark blue jacket – with or without lapels – the collar with two golden galloons on each side.
Gold epaulettes, like a colonel.
White or chamois breeches going into high black riding boots.
Blue belt with gold edging.
Regular Adjutants – as above, EXCEPT:
Pointed cuffs, collar and lapels (when worn) – light blue.
Epaulettes by rank of wearer.
For the Emperor's own adjutants:
Light blue coat with light blue facings trimmed silver.
Silver epaulettes with silver aigrettes/lanyards on right shoulder.
Red vest with silver cording.
light blue breeches with silver trim, going into black hussar boots with silver trim and tassel.
Adjutants wore arm sashes on the upper left arm, colored by staff level:
Brigade: light blue sash plume green over blue
Division: red sash with red over blue plume
Corps/Army: white sash with red over blue plume.
The sashes may have had gold embroidery (leaf shapes) along the top and bottom edges.