Stuff like "Angel of Heaven" never really translates well, just pick characters that can have the pronunciation which match your daughters name. I am not sure how your daughter's name is pronounced though.. .. so just guessing here but you would want characters pronounced "i" い "o" お "na" な "sei" せい "lo" ろ
But I would highly recommend you just get it in Katakana because nobody will understand what you mean.. イオナ セイロ