Why do you think a visual description is the most relevant?
We don't know the large scale shape of the universe (whether you want spatial cross sections of the whole four dimensional structure). But, locally, space seems to be very close to flat except for effects of gravity.
I've been thinking about the flat shape of the universe. We see pictures of the universe as such now. It has changed from eternal and everywhere in infinite directions (I suppose it could have been designed as round or rectangular. I don't know.)
I think the above shape is correct, but the labels are not as well as the time. The universe is expanding in a vector direction and in all directions equally. If we look as it from the end, then we can see that the universe is flat. All the stuff inside is Planck constant, Higgs field, boson, the stars, planets, moons, black holes, and more. I agree about the gravity and think this is the overall description except the labels are not. What do you picture?
In the above diagram, the universe looks elliptical, too. What do you think i