If the sheep are a block of color (without the background color going through) then you'd be knitting intarsia style. You'll have one strand of the main color up to the sheep, then have a strand for the sheep, and a strand for when you pick up the background again.
When you switch colors, you have to hold the yarn you're stopping over to the left on top of the hanging strand for the next section to twist them and prevent a hole.
You might want to consider making the scarf double wide and fold it over to seam it up the side. The back of intarsia never looks as pretty as the front.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo