Cable Pattern

Hi everyone…can you do cable pattern in only one color? I want to switch colors after about 3" but I am seeing the color change on the purl stitch: R1,3 (RS) k3,p5,k6,p5,k3
R2 & all( WS) k8,p6,k8
R5 k3,p5 sl next 3 to cable hold in back k3,k3 from cable p5,k3
R7 rep R1
R8 rep R2

Thanks for your help!!! Cheley