SASARCHIVER;
The colour BUFF reference is actually a colour in the Tamiya Acrylic paint series. It is paint number XF-57 BUFF.
The "Pink" colour referred to is an actual colour used by the British Army BS Pink. It apparently gives a better concealment than sand colour, due to the reddish reflection at sunset or sunrise in a desert environment.
To create this colour use the Buff colour and add Red gradually to it to achieve a "Salmon" colour of pink. The instructions of Tamiya's kits usually include painting/marking instructions even if they are printed in Japanese use the XF# to determine the start colours.
I hope this helps. As well if you enter into a search on the internet, I used "Special Air Service" "Pink Panther" and it turned up various hits that led to different reference photos including colour photos of actual vehicles, unfortunately I did not come up with any in "Pink" (Short search for me) but I'm sure if you sift through you will find some actual photos to assist in the build.
As far as the question you had on dust/mud follow the advice already given. I would add that if you wat to "chunk" up a bit of dried mud in the wheel wells I use baking powder and a small amount of white glue. I brush on the white glue in the wheel well and then sprinkle a small amount of baking powder on to the glue. I continue the process until I "chunk" the area enough to my liking. Then I spray the area with the appropriate colour to simulate the terrain, BUFF thinned and lightly misted works well for a fine dusty look.
Hope this helps with your build.
Cheers;
Gregory