You can't do it with a reflexive pronoun 'herself', but I daresay "She always expresses her personality in her choice of clothes" might work.(Context) She always wears peculiar clothes, hair color, and glasses. Her fashion is always funny or odd, and it reflects her personality. She has a funny or peculiar personality.
She always wears formal and decent clothes. She has a very strict and taut personality. Her fashion always reflects her personality.
In these cases, can we say, "Her fashion always expresses herself" ?