You're going to have to crank the ISO up to at least 6400 and use the widest (most open) aperture your lens has. I'm guessing 5.6? Set your shutter speed to overexpose about 1/3 to 1/2 stop. Experiment with this. Hopefully you'll be able to freeze the action. It's going to be tough with such a slow lens. Shoot raw and use auto white balance, as many times the lights pulse, and the color temp will change from shot to shot. Shooting raw you can correct color shifts in post. Good luck.
It's a Canon 40D... ISO is normally 100-1600. If "expanded" mode is enabled, it can go to 3200 but it's called "expanded" mode because even the camera maker doesn't think you'd normally ever want to use that mode due to the intense amount of noise you'd have in the resulting images.
In the end, you've got to be able to use a high enough ISO and then collect enough light for that ISO *while* keeping a fast enough shutter speed for the action.
"Fast enough" shutter speed is usually about 1/500th sec (faster is preferred... but below 1/500th sec it gets hard to freeze action.)
As I sift through Flickr looking for football (at night) shots, I see examples where I can translate exposure values to EV 6 (mid-afternoon sunlight is EV 15 -- so that's 9 stops lower. Each "stop" is half the light. So that's 1/2 of 1/2 of 1/2 etc. ... 9 times out. Or "roughly" 1/500th as much light (just so you know what you're up against.)
Suppose you max your camera ISO to ISO 1600 (ignore ISO the "expanded" ISO of 3200 because I'm pretty sure you'll hate how much noise you have.) Suppose you have a 70-300mm f/4-5.6 lens. At 300mm you're at f/5.6 (frankly you're at f/5.6 by the time you get to 200mm). To get enough light at ISO 1600 using an f/5.6 lens you'd have to slow the shutter speed to a mere 1/30th second shot. That's NOT going to be adequate to freeze action unless the camera is on a tripod and the subject is standing still.
If you had an f/2.8 lens, you could make it to 1/125th second. But that's still not really fast enough. You need to be able to bring the ISO up to about ISO 6400 (even with an f/2.8 lens) to achieve 1/500th sec. but that's beyond what a 40D can do. At f/5.6 you'd need to bring the ISO up 2 stops faster... ISO 25,600. It turns out some modern cameras actually *can* do that. Of course at those high max ISOs you do get noise... so being able to use a fast lens will allow you to drop the ISO down to ranges where noise isn't really a problem.
The 7D has had quite a huge price cut (in anticipation of the announcement of the 7D II -- which we actually think may be as soon as next week.) A 7D is strongly preferred because the camera is optimized for action photography such as sports. BUT... even a 60D (which has also had a huge price cut) has the same sensor and ISO capabilities of the 7D but it has the same focus system as the 40D (9 point AF where all 9 points are "cross type" even at f/5.6). The 7D, on the other hand, has 19 AF points which are all "cross type"). The 7D has a vastly faster continuous shooting speed (8 frames per second.)
You may want to call Canon and ask them about their "loyalty program". This allows you to trade in your 40D for a discount on a newer camera (the camera you trade in does not need to be a "working" camera.)