You can simplify the coding preparation by just getting a basic LeetCode subscription, filtering down to problems asked at Facebook in the last six months, and then sorting by frequency (how many times each question has been asked recently, according to user reports). CLRS, etc., are nice books, but if you're seriously considering a senior role at Facebook presumably you already know the basics and just need to memorize all the tricks for LeetCode problems.

For system design, though, it actually is worth reading through "Designing Data-Intensive Applications."