I don't know myself, because I'm not a nutritionist, but my basic understanding is that there are three purposes to a post workout shake. First, rehydrate; second, restore glycogen stores (with carbs); third, metabolize protein to stimulate muscle growth.
For post workout I drink one scoop of Optimized Nutrition Whey protein (protein and hydration) and eat a banana and maybe a slice of bread (carbs).
From what I've read (and it is disputed) this post workout meal is most effective if done within about 45 minutes of the end of the workout. The nutritional content will vary based on what type of workout you're doing and your goals. You could classify Insanity workouts as endurance exercise (technically they are HIIT strength and cardio exercises) which would probably mean you need more carbs and less protein. However, if you're doing the strength exercises to failure and dogging it on the cardio portions and your goal is muscle mass, more protein, less carbs (although, taking more than ~25 g of protein in one meal is probably not more effective).
Further reading:
http://breakingmuscle.com/nutrition/whats-the-best-recovery-drink-for-multiple-workouts
http://breakingmuscle.com/nutrition/lets-talk-about-protein-when-where-and-how-much-do-you-need