If that qualifies then surely symbolic notation itself is also a visualisation. It's not as if it's just a syntax tree, quite a few properties (associativity, distributivity, symmetry) are suggested purely by the way we denote sums and multiplication.
If you wants things to be even more visual you could use Penrose diagrams [0], though I don't find them particularly intuitive.
It's really the "more advanced" way to do it. There are a lot of people, myself included, that are actually much better at thinking in abstractions - I suspect the author might be the same, despite her thinking of over-abstraction as a barrier.
If you wants things to be even more visual you could use Penrose diagrams [0], though I don't find them particularly intuitive.
[0]:https://en.m.wikipedia.org/wiki/Penrose_graphical_notation