It was once common to offer different finishes to extinguishers to match the decor of the house or business premises in to which they would serve.
Minimax offered Signal Red, Maroon, White and Leather clad, but Merryweather's Konus Kemik was offered in many different finishes - I have a 1920's brochure illustrated with various metallic, polished wood effect and art deco colours to suit almost every environment.
Even as late as the 70's Hoover installed new special made Copper 2 gallon and Chrome 1 gallon water extinguishers for their Glasgow HQ (Ii've been lucky enough to salvage a quantity as the building was cleared by Hover on leaving).
The key is that those most likely to use them can quickly identify them - if all the staff know that the purple cylinders with the polished brass pictogram sign above them are AB class Foam fire extinguishers then it shouldn't be a big issue.
