Most of ours are to do with transracial/international but not actually of my DDs ethnicity and she doesn't seem to care :) I think stories about adoption - whether they really reflect your eventual child's life story or not - are great to have as they simply normalise adoption and give your child the language to talk about it.
We like 'A Mother For Choco' and 'I Love You Like Crazy Cakes'. Also love all the books by Todd Parr but especially 'We Belong Together' (specifically about adoption) and 'the Family Book' - loads of different families and ever so matter of factly there is the adoptive family. So lovely and colourful - all of them! Both of mine kids love Parr's books and ask for them over and again. Something about his illustrations just grabs them and makes them feel good :)
Another great book by Julia Donaldson (of the Gruffalo) is 'Monkey Puzzle' which is simply about how Monkey is lost and looking for his mummy with the help of butterfly. Butterfly points out loads of animals and Monkey keeps saying that can't be his mummy as the tail is different, or the legs etc - they don't look like Monkey so can't be his mummy. In the end, butterfly says something like 'none of my babies look like me.' I just got it for the DDs because I like Julia Donaldson's books, but the first time I read it, it was like 'wow, she wrote a book about adoption without even realising it' :)
We also like 'Over the Moon' by Karen Katz which is about adopting their daughter from India. I remember showing it to the psychologist during the prep course and he loved the illustrations, commenting how much positive energy they had.
'Tell Me Again About the Night I was born' by actress Jamie Lee Curtis is lovely but may not be everyone's cup of tea :)
We have used some of the books for older children but my oldest is only rising 6 so we still mostly use the younger ones. However I have found 'We Are Adopted' useful in many respects.
Happy reading :)