That graph is confusing.
It's incredibly fucking confusing, in part because it's using two axes to discuss one-and-a-but issues that aren't completely aligned (social politics, mostly, with occasional economics).
Modern American liberalism is essentially the background radiation from the New Deal and the civil rights movement. Modern American conservatism is the increasingly distorted simulacra from the Reagan administration and the Moral Majority. Despite everything gobshite TV pundits will tell you, liberalism and conservatism in the US aren't exact opposites, so they don't map precisely (hence why some of those text labels are a bit tortured). And ironically enough, it's conservatism that is both newer and, in many respects, the more radical and transformative ideology.
It's probably because of these labels - "liberal" and "conservative", that suit neither side of the aisle well - that American political discourse seems to get so garbled. Some Republican voters are conservatives in the proper sense, but many are reactionaries. And sure, some Democrats are liberals, but some are moderates or centrists, and a few are (shock horror)
democratic socialists.