Biking is all about leg strength. If you need more speed, make your legs stronger. Concentrate on quads, making sure to balance that with hamstring strength so you’re not imbalanced.
Many pro riders ride with a fast cadence, around 100 RPM. If you’ve got a cadence meter, use it! Riding at a higher cadence allows you to use your endurance muscles (the slow twitch fibers) instead of your sprint muscles (the fast twitch fibers). Your sprint muscles won’t last very long!
Use aerobars. The less wind resistance you have, the faster you can go for the same amount of strength.
Bike position. Ideally you want to be positioned on your bike in such a way that the combination of aerodynamics and comfort is maximized.