Hello!
I am reading your example step-file wavy-cube.stp
The file has two STYLED_ITEM with name 'color':
#191 = COLOUR_RGB('',0.321568635616,0.341176475329,0.431372551983);
#206 = COLOUR_RGB('',0.745098043297,0.325490203104,0.133333336917);
my code:
STEPCAFControl_Reader Reader;
...