To be truthful, it is well worth looking for a book or books on the subject of the Napolionic Wars as there are many available, which will assist you in getting all of the different colours that composed the 'Guard' Uniform.
The Imperial Guard figures look really imposing when painted and are one of the best known of the French Forces.
You may care to look at the Osprey Books which offer excellent value for money.
http://www.ospreypublishing.com/title_detail.php/title=P6620 Good luck in your first project.
John