I have some uniform paintings containing images of the field offices of that regiment. They are depicted in similar frock coats with sleeve trim and yellow collars,but also have rank on the collars. if you can find the book Military Uniforms in America 'Long Endure: The Civil War Period 1852-1867 you can see an image of it. The plate was rendered by Frederick P. Todd, considered an expert on uniforms. He states he based the uniform plate on a woodcut in Harper's Weekly for 27 Sep. 1862 from a drawing by Alfred R. Waud. Later uniform studies would have largely been basses on Mr. Todd's work. The following are 1st Virginia officer uniform plates I have that may be considered honest attempts to be accurate, but again most are likely at least partly bassed on Mr. Todd's original work:
The United States Cavalry by
Urwin, Gregory J.W.
The Iron Brigade by
Selby, John
History of the U.S. Cavalry by Johnson, Swafford
U.S. Cavalry by Selby, John
le dostume et les Armes des Soldats de Tous les Temps by Funcken, Liliane and Fred
The History of Cavalry by Grvasic, Z. and V. Vuksic
I have maybe another 8 to 10 images on posts cards, and other very unreliable sources which are certainly based on the above sources and were not really researched by the artist. There are perhaps another 10 to 15 sources which would show enlisted uniforms of the 1st Virginia.