import FreeCAD
import random

# build a dictionary to store values and associated colors
colordict = {}

# iterate over each object in the document
for obj in FreeCAD.ActiveDocument.Objects:
    
    # only consider objects with IFC properties
    if hasattr(obj,"IfcProperties"):
        
        # search for the FireRating property
        # properties are stored as "PropertyName;;Pset" = "Type;;Value"
        for key,value in obj.IfcProperties.item():
            propname,pset = key.split(";;")
            proptype,propvalue = value.split(";;")
            
            if propname == "FireRating":
                
                # look if this value was already stored in colordict
                if propvalue in colordict:
                    # if yes, just attribute the color to the object
                    obj.ViewObject.ShapeColor = colordict[propvalue]
                else:
                    # if no, create a new color as a tuple of 3 float values (r,g,b)
                    newcolor = (random.random(),random.random(),random.random())
                    # store that color for reuse
                    colordict[propvalue] = newcolor
                    obj.ViewObject.ShapeColor = newcolor

# upon exporting again to IFC, colors will be kept automatically