From the Knit Picks Website:
A delightful play with colors much like finger painting pleasures long forgotten. A teleidoscope is particularly handy for selecting your colors for this mosaic-looking scarf.

Ed. note: The mosaic look is created by alternating colors worked in seed stitch. There are no slipped stitches.

Knit Picks pdf modified April 23, 2007

Yarn:
Knit Picks Merino Style discontinued
(100% Merino Wool; 123 yds/50 gm ball):
5 colors, 123 yards each

Needles:
Size 6, 47” circular needle

Cabled cast on recommended (directions provided). Design features Looped Fringe (made from dropped stitches).

From the pattern:
The scarf for these instructions used five colors. I absolutely loved the result. I did find that I had to monitor the sequence of colors more than I would have liked. I think that seven colors would have made it so that I would have been able to grab colors randomly without having to make adjustments as often. You may find that you want to work with fifteen colors that are all very close in tone with just a couple of accents.
It is all up to you. The teleidoscope is the key to having success with your colorful explorations.

From Wikipedia
A teleidoscope is a kind of kaleidoscope, with a lens and an open view, so it can be used to form kaleidoscopic patterns from objects outside the instrument, rather than from items installed as part of it.