Now that's a great picture !
Michel, I did some research for you. It may not be 100 percent accurate but it should be a good starting point.
To begin with, here's a partial list of German colors used, along with the "Xtracolor" numbers as a reference. To add a little confusion to this, the RAL colors changed in the early 1950's and sometimes the wrong color numbers were used later in reference materials.
This next photo shows an approximation of German RAL colors as compared to the US Federal standard colors. Please keep in mind that the colors are not an exact match.
Next I did a little cross referencing and found a Revell of Germany color chart that actually lists Afrika Braun as a color.
This listed a FS (Federal Standard) number next to it.
So I took my almost completed Panzer III which I sprayed with Model Master Afrika Braun as a comparison placed next to the color chip in my FS book.
You can see the results from this in the picture below.
Another picture but closer ...
I would consider starting out with Revell of Germany color number 32117 and possibly lightening it or darkening it as needed to get you in the ballpark.
Hopefully this will help you with the color scheme.
Merry Christmas my friend.