IFC-files have "Layers" in the same way as Autocad has.
This function allows you to set the layer standard for the exported IFC file.
It uses the exact same layer-standard file format you use on DWG export.
Select one of the supplied layer standard files.
Or the file you already use for DWG export.
And make this your Layer standard for IFC export as well.
(NB You need to restart Revit for the change to take effect.)
You can also specify/override these layer names in Element Type Properties on the parameter "IFC CAD Layer".
Either manually or set an automated job for Naviate "Combine Parameters" to do it.
If you dont have that parameter just run "Create IFC Parameters" to get it. (2016 version)