Miss Deborah's clothes are very plain and reflect her serious nature. They are definitely much less colourful and pretty than Miss Matty's.
In this picture she is wearing a plain gray-brown gown with a flat pointed collar and a button front. She wears a black shawl and her usual white cap. Elizabeth Gaskell described Miss Deborah's bonnet as a 'jockey-cap' and it definitely looks like one. See below.
It doesn't have a very extended brim and is very loosely tied.
This is a shamefully short post but unfortunately I couldn't find any pictures of any more of her clothes!
I hope you enjoyed reading!