couple of things you can try:
start out with your shoes looser so your feet have room to swell. Make sure your socks allow for swelling also: no tight cuffs or elastic bands. Also you may want to consider switching out your insoles. I use running insoles in my shoes. I also flex and splay my toes while I'm riding so the feet aren't so static. I stop about every 1 1/2 hrs to eat and take off my shoes. I usually try to walk around in my stocking feet during that time especially if you can find some grass - it just seems to feel good on my feet!
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"