Freemotion have a load of rides that they can tell you about when you hire the bike, most start with the road out the north of playa Del lngles that me hero mentions. Have a look on bikely, strava etc for the routes so you can get them on your GPS before you go.
My wife is from las Palma’s so I’ve been loads but only ever done one ride. It was in the summer and very hot, I had to stop to buy water to pour on my head! You’ll be OK at this time of year but it will still be warm. Once out of town (about 5 mins) the roads are amazing, so smooth, twisty and quiet. I hired a cannondale super 6 and rode up the mountain turned left and came back down and back along the old coast road, about 40 miles and it was a great ride. It was the 6th one down here.