We usually chose the natural colour, a sort of creamy off-white wool.
But we knitted my father a royal blue one, and I did myself a soft green-coloured one in my teens. They're blooming thick and hot, excellent during the coldest winter months.
I don't know if people knit much nowadays? I knitted all my school uniform cardigans when I was ten. And when I was only six, I knitted my teddy bear a natty little pair of pants in pink wool as I was a bit ashamed he had no clothes. I was showing him to my neighbour only yesterday, and she was very impressed!

Isn't there a funny song that goes something like:-

See the old lady knitting,
Knitting as fast as she can.
What is the old lady knitting?
She's knitting a little old man!