I taught intro courses on graph theory at IISc (in 2024 and 2025). During this time, I was also working on my book - Graphs, Games, Algorithms. In 2020-21, I spent a year teaching Linear Algebra, Graphs and Algorithms at the University of Hyderabad.

Better Way: uses puzzles to introduce core principles
Way Better: covers classic algorithms
The Unreasonable Power of Linear Algebra: showcases algebraic techniques
Senses of a Graph: surveys major themes
This is intended to be a short fun book covering graph theory and algorithms, designed to be useful irrespective of your major. Feel free to send me feedback.
There are a lot of books and lecture notes out there, each having their own style and content - I recommend checking out and finding what suits your interests.
Basic to Intermediate, highly readable (where some chapters cover graph theory):
Invitation to discrete mathematics - Matousek, Nesetril
Algorithms illuminated - Roughgarden
Algorithm design - Tardos, Kleinberg
The discrete mathematical charms of Paul Erdos - Vasek Chvatal
Some other popular textbooks are by Douglas West, Bondy and Murty, Harary, Bóna
Intermediate to Advanced:
Graph theory, Diestel
Spectral and algebraic graph theory, Spielman
Also check out the following talk: Miracles in Algebraic graph theory by Spielman https://youtu.be/CDMQR422LGM
Specialized topics:
Two sided matching - Roth, Sotomayer
The game of cops and robbers on Graphs - Bonato, Nowakowski
Advanced:
The Probabilistic method - Alon, Spencer (The book for the probabilistic method)
Erdos on Graphs - Chung, Graham (contains many open problems)
Enumerative Combinatorics - Richard Stanley
Some resources for puzzles/gems:
Proofs from the Book - Aigner, Ziegler
33 miniatures - Matousek
Algebraic combinatorics - Stanley (there is a section called Mathematical gems)
Mathematical Puzzles - Peter Winkler
Also recommend checking out people who wrote widely (and well) on recreational mathematics - Henry Dudeney, Sam Lloyd, Martin Gardener, Ross Honsberger, Peter Winkler
A list of famous algorithms:
https://cstheory.stackexchange.com/questions/189/algorithms-from-the-book
Science Writing:
Here are a couple of engaging talks on science writing that I found extremely useful. Both cover different ground, so check them both sometime.
Larry McEnerny: https://youtu.be/vtIzMaLkCaM
Judy Swan: https://youtu.be/jLPCdDp_LE0