The symbols ∧ (AND), ∨(OR) and ¬(NOT) are very abstract. Using them in a diagram makes that diagram harder to understand intuitively. You sort of have to already know them to understand what is going on. Also more complicated diagrams require a lot of mental effort to parse, which is in stark contrast to the other chapters, where diagrams are elegant and intuitive.
I would like to suggest other symbols:
NOT
Have a red? curly? zigzaging? ring around the elements. This would work great for composition and would be easy to read even in more complicated diagrams (like when illustrating the rules of de morgan).
AND
Have a rounded rectangle around the terms, signaling that they are connected and are now one term. A bit similar to a cartouche in egytian hieroglyphs
OR
Have a rounded rectangle around the terms, but with a line separating the two terms.
Example
To illustrate how easy these symbols would make visual parsing I have drawn a diagram of the de morgan rule:
x OR y = (NOT x) AND (NOT y)
![de morgan](https://user-images.githubusercontent.com/3586246/138570858-997bc457-a25c-46ec-bc0d-d7856bd03333.png)
(drawn in paint, I am ashamed by myself)