The fuselage is supposed to be pearl gray, something similar to American but slightly lighter. The model looks OK to me.
The red on the engines and tail seems to be quite metallic on the real thing, which means it changes the shade depending on the angle or light. Sometimes brighter, sometimes darker... maybe looks too bright on the model but It can just be the lighting on the picture.
The OAI logo on the tail looks quite golden on the model, but I really hope that's just some kind of reflection, since these titles seem to have a shade effect on them. They're supposed to be quite silver, I guess? Anyway, I think this model looks good overall! It's a nice one.