There are a huge number of unknown factors based on your riding experience, training history, and equipment.
Essentially the equation for determining cycling speed on a flat road is: Power - Drag = Speed.
Training will make the biggest difference in your time but it takes a lot of effort over a relatively long period of time. Equipment can make an immediate difference but costs a lot of money and won't make as big of difference. That said, depending on your goals, you should consider what both will offer you in improving your time.
Aerodynamic drag. Your body is the biggest source of drag when riding, so simply having your position assessed can make a big difference (30 seconds to multiple minutes). If you are riding a standard road bike, adding aero bars will be part of achieving the ideal position. Once your position is improved, you can consider equipment such as helmet, frame, and wheels, and other parts that are build to limit aerodynamic drag.
Power. Aside from basic position changes, maximizing the power you can sustain for the 40 km will make the biggest difference. Not knowing your training history, it is hard to provide you with many specifics, but in the end you need to improve your sustainable power output. Doing intervals for 60 seconds to 5 minutes may have some beneficial effects for 40 km TT, but they focus on your anaerobic capacity and improve the amount of oxygen your body can transport to working muscles (usually referred to as "VO2") rather than concentrating on sustainable power (sometimes referred to as functional threshold power or FTP). To maximize your performance at 40km you need to do longer intervals. The classic FTP-increasing workout involves doing repeats of 20 minute intervals, usually with 10 minutes easy riding between. You simply ride at the fastest sustainable speed you can for 20 minutes; do not sprint the first few minutes only to fade, but rather try to find a speed you can hold consistently for the whole effort. Depending on your fitness you may not be able to do multiple efforts of 20 minutes--even if you "can" it may not be a good idea if you haven't worked up to it. So start with 8, 10, or 12 minute intervals and work up to 20 minutes. Over time work up to two, occasionally three of the these intervals in a single workout.
If you haven't done any interval training before, then these workouts may be months in the future for you because you'll need to simply ride consistently, increase the hours/week you're riding, and add some intensity to your workouts. But with a 72 minute time for a 40km, it sounds like you've got some experience and may be able to begin working up to the 20 minute efforts. If you have any questions, consult a coach (and maybe your doctor) before engaging in any intense training.
Good luck and keep up the hard work!