1901 Standard
1935 Standard
Colour. Black, dark grizzle, slate, sandy, or an admixture of these colours with white. Color - Golden, sandy, honey, dark grizzle, slate, smoke, particolour, black, white or brown. This being the true Tibetan Lion-dog, golden or lionlike colours are preferred. Other colours in order as above. Dark tips to ears and beard are an asset.

As the first standard implies, there was no particular color favored by the Tibetans,  however in England the notion of the "lionlike" color being the appropriate color for the "lion dog" was introduced in the 1935 standard.  Modern standards have abandoned color preferences, but some fanciers regret that  most modern Lhasa Apsos have lost the deep, rich colors and black tippings  seen in earlier times.