I recommend drawing out the maze for your own use, but not letting the players see it (at all) - their characters are too busy moving to stop to map the thing!
Once you've got your maze mapped out, split it into zones, where each zone is roughly the distance the party can cover in 1 round/minute/whatever. (I recommend going for 10 minute blocks, and assuming that a pause for a combat or other encounter counts as 10 minutes.)
For each zone, try to provide:
- Some characteristic that you will mention when describing the zone. Try to make each zone unique, but because it's a maze make them all maddeningly similar - that way, clever players can pick up in when they find themselves back in the same zone again (and potentially use that to navigate), but they have to be really on the ball to spot it.
- Exits to three other zones (the one they came in by, and a choice of two others). Not every zone needs to provide a choice, but most should.
- Something they can use in an attempt to increase their speed. This doesn't need to be obvious, and you don't even need to know up-front how it might be used, but there should be something!
- Something they can use in an attempt to slow pursuit. This could well be the same thing as above.
Some zones should also have obstacles/encounters to slow the PCs themselves down.
In gameplay, I would recommend having the pursuit start 2 zones behind the party, and move at the same rate. However, if the PCs are successful in speeding up or slowing pursuit, each success increases their lead. Conversely, if they stop for a combat, a trap, or to heal up, the enemy gains by a zone.
And be sure to define end conditions for the chase - on one hand, presumably it ends when the pursuers catch the PCs, and they face an overwhelming encounter. But at what point do they escape? Is there a defined exit that they need to reach? Is there a minimum separation that they must achieve, at which point the enemy gives up? Both? Something else?
I should note that the above is quite a lot of prep work up front. However, it should pay off in play - the players will have interesting choices galore to make, while for your part you'll always have a clear idea of where the PCs are in the maze, how to describe the current zone, and a variety of ways to make the chase interesting.