More wood method: Start with an oversized rectangular legs (in width) and cut mortises on the legs (under this method, the mortises are parallel to the edges) as if the legs were to be attached to the mitred aprons at right angle in the usual table construction. Then cut the oversized legs to the desired splay shape/angle.
My method: Cut the legs to the final shape, then cut the mortises on the legs where the mortises are perpendicular to the floor. See images. For dead precision, I used a cradle to position the DF500 in place.
To refine your techniques, try it on a mock-up first.
Lastly, the button mortises on the aprons were cut with the DF500's wider setting.