I suppose it might partially depend on what the official name of the United Kingdom is and if it still has Ireland in the title or not. Really, wouldn’t it also be the only dominion that could count as a Kingdom. Not that they had their own Crown Jewels, history of unified rule by their own people, or stuff like that. Depends what we count the Ascendancy as.
My old QBAM map for Irish Independence depicts a different political scenario (OTL) than Home Rule, but this map has a number of different ways to represent it. You could do a British-colored island with an Irish-colored outline, you could do the reverse as others have pointed out, or you could do my personal aesthetic preference which is the Irish-British alternating stripes which is represented by the Anglo-Irish treaty on this map. I think it could be good because it represents the distinct nature of Home Rule as opposed to dominion status, client-statism, protectorate, colony, etc.