Get yourself some good long johns. Not cotton ones, but synthetic quick dry ones that are stretchy, so They don't bunch up. This will keep your skin dry, and therefor, less cold when you stop riding, or the wind hits you.

For your next layer, You can switch things up depending on the weather. I have a heavy knit wool sweater and a thinner fleace one.

For the outer layer, a softshell jacket is all you need, to keep the wind off you. For your pants, a good pair of Nylon windproof pants is good down to -30c

Also, wool socks are essential, you will freeze in cotton.

I have rode my bike in -40 weather with this, and I havn't froze yet.