Weighted graph it is.
I’m struggling to automate the drawing of such a graph – not because it’s complicated, but just my skills, in that respect, aren’t up to much.
I think the image could convey the bigram, trigram and n-gram relationships, as they’d all form a continuous path between numerous points, better than a grid of numbers. But I need to produce one to be sure. Unfortunately I’m not going to be around for a few weeks.