Here’s my diagram for Romans 3:27-31. The words in grey are grammatically assumed, meaning that they are not actually in the Greek text, and most English translations also reflect the sentence fragments. But when all the expected words are included, especially in verse 27, it really seems to be making a point about boasting (spoiler: boasting is right out).
And the English block/outline (also with grey as inserted for sake of complete sentences):
