Hi Sarah,
It's hard and I'm sitting on both sides of the fence. I am both a parent and a nursery nurse/ manager of 18yrs. I am afraid that there isn't an easy way out if yr child is tearful, it's about perseverance. Did you have a settling in period before she started?
1. Sometimes it's good to let her have a toy or comfort object from home for her to "look after" or to "look after her".
2. She will have a key person in the nursery - when my son was playing up (having attended from 6mths) I would make sure that I went in a little bit later when she started her shift and picked him up slightly earlier for a while.
3. Always say goodbye to her and don't disappear as that makes it harder when she realises you're not there.
4. Try to give her a time when you will be returning ie. teatime or after sleep time, something so that she can relate to (not sure how old she is).
To be honest very few children cry the whole time, I had one child in a nursery where I worked who told her mum if she took her to nursery she would cry all day and not play with the other children. She cried when her mum left her and somehow knew to start again about 10mins before her mum arrived - guaranteed she would do it & I know her mum thought we were lying until I took some pics of her playing and eating lunch 
It is hard and I never fully appreciated how hard until darling son number 2, who wouldn't even go to my mum much less a stranger !!!!!
Take care and if it goes on for longer than a couple weeks then maybe reassess the situation.
Aliaj xxx