Hi,
There are a lot of pictures of him out there in black and white but I have seen some nice color pics too. So if you can find a copy of Kenneth Macksey's book Rommel, Battles and Campaigns you will be able to veiw a very nice set of pictures of him on the inside of the cover in his Africa Crops Tunic and one of him from the field in shorts and a field grey uniform. Brigadier Peter Youngs book on World War Two has a color picture of him but there are not a lot of them around that I know of but I expect a quick trip on the web or to the local library will lead you to some good pics but my thoughts would be to go for a faded field grey look. I have also seen him sporting a checker pattern scarf with a long field trench jacket on as well as a tunic that looked like it was probably the desert tan they wore this is a guess since it was black and white and he could have been in faded field grey with a ton of dust layered on for good measure. Hope this helps a bit.
Dave