On my opinion, Isometric drawing extracted in the Isodraft is intended as a guide for piping fabricators. With this in mind, I think it would be undesirable to mix different piping types together in a single sheet of isometric drawing. I think that this is the reason why there is no feature to make color-coding in isodraft isometric based on fluid code.
Instead of using Isodraft isometric drawing, I think that you can use Draw to achieve your requirement. You can make a View in draw in Isometric angle and use representation styles to implement color coding. However, if you also need piping material table from isodraft, then you need to figure out how to get that data Isodraft, either manually or by developing a macro.
