From my perspective, computer science (as an academic field) embodies two concepts maybe more than any other, and does so maybe more than any other discipline: problem-solving by reduction and abstraction.
Reduction is about breaking apart a problem, identifying easier subproblems (maybe but not necessarily recursive) whose solutions can be combined or translated into a solution of the original problem.
The concept is pervasive from software engineering (modularisation of systems) all the way to TCS (reduction as an algorithm design principles; creating structure in problem classes by reduction techniques).
Abstraction is about generalising a given problem by relaxing or creating parameters, switching to application-independent terminology, and maybe ignoring some constraints for the moment. Then, solve the resulting, more abstract problem and use the insight gained to solve the original one.
This also happens everywhere in CS, from general-purpose programming libraries to algorithm design principles.
How may this look like visually? I note that the two concepts are somewhat dual to each other. One narrows, the other broadens scope. Hence, I think complementary triangles may work nicely.
The inscribed triangle (left) displays one triangle for abstraction (orange, inner) and one for reduction (blue, outer) reading from bottom to top; the image works the other way around as well. It is a clean design I'd expect to work well (visually) in most circumstances. The four resulting areas highlight the plurality of CS as well.
The overlapping triangles (middle and right) work from the same basic idea but represent both concepts equally large. In addition to plurality, we now have distinct parts (only blue or orange) but also an overlapping part (both colors) which represents that there is a common core in CS, despite some fields being very far apart from each other in terms of methodology.
Colors are left for the designers to pick, obviously (I happen to like the blue-orange combination, personally). The overlap diamond should probably have proper color mixing going on.
This has partially been inspired by the very simple yet fitting logo of crypto.SE; read the designer's thought process here.