This cardigan is knitted top down in one piece. The button band ribbing is picked up and knitted afterwards.

The pattern was designed specifically for stripes, so it is a plain, garter stitch pattern with minimal stocking stitch
detail on the raglan stripes. You can however knit it in one colour; there is after all no rules.

If you do decide to change
colour, and you want a clean stripe, make sure you change colour on a right-side facing row.

Colour changes are not specified in the pattern. Your canvas is blank; colour it any way you like.