Improving your standing long jump will also improve your speed and power. A more explosive, powerful athlete will be a faster athlete. Improve both your standing vertical jump and standing long jump and you will be faster and more explosive.
The NFL Combine 40-yard dash results for the last 10 years shows that those with the best standing vertical jump and the best standing broad jumps have the fastest 40 yard dash times. And, if you improve your running mechanics, you will be even faster! But, explosive power is very important. DURING MY PLAYING DAYS, SOME OF THE FASTEST PLAYERS ON MY TEAM HAD TERRIBLE RUNNING MECHANICS!
Other than squat jumps and weighted squat jumps, use exercises like depth jumps, distance skips, height skips, leg bounds and ankle hops to improve your vertical and long jumps.
I recommend doing plyometric work 2 times a week and speed work 2 times a week. Strength work can be done 3 times a week. You should do your plyometric work on the same day that you do lower body strength training. Lower body plyometrics would be done before your leg strength work because plyometrics are done with maximum effort.