Almost all Waka grade kavas (waka being purely lateral roots and no crown roots) I have tried have been very light in color, sometimes a white but usually in between yellowish to creamy whitish. Where you'll find most kava not marked as waka grade will be made up primarily of crown roots and in turn has been much darker in color, but not always, so there's other variables.
As for the roots being peeled Gray Owl is absolutely right, I've bought rootlets from two suppliers now and from a little experimentation on my part, I found out what was up with darker varieties. If you ever look at the finer kava particles sitting at the bottom of a shell, or leave an empty kava bowl overnight and look at it in the morning, you might find what looks very much like 'black sand'. I think that the root cause (pun intended) of darker kava is the roots not being peeled. When I would strip my rootlets of bark before grinding, the kava was white - yellowish, when I would not strip the bark, it was definitely darker and sometimes a dark cocoa brown. Not to mention the bark gives off a huge amount of the earthy taste in kava, whereas without the bark would be the primary source of the kava's taste itself.