I don't believe that's a thing anybody can do. I'm pretty sure a driver's image/persona is locked as soon as it is created. The only thing that is change-able as of today is name and nationality. Imo that's enough considering what people do to driver names already, let alone what they'd do to their appearances!
Leo is correct you can't change a drivers image and if you could based on what some people do with the drivers name as mentioned earlier, I'd hate to see what they do with the pictures.
If I were you, I'd go to the suggestion section and make a suggestion of being able to make changes such as adding hair styles, male / female, skin tone and such, similar to like how you would create an avatar or mii on the Wii. It's a good suggestion, but once it isn't the uploading of an image.
