Sayori is initially portrayed as the character archetype of a Genki Girl, expressing a bubbly and cheery disposition. She is very clumsy, noted for finding ways to accidentally hurt herself or to drop random things. Regardless, she is shown to be a jokingly cunning individual. She states that writing poetry and studying literature is different to her than other interests because it helps her explore her feelings.  It is later revealed that she suffers from bad depression and works so hard to make the people around her happy to cope with her own lack of self-love amongst other things. (Description pulled from the fandom wiki)

Her voice should be on the higher side, but not so comically high pitched that her more emotional moments come off as comical and unfitting.  She should be carefree most of the time, but her lows should be emotional and moving