You may need to water daily for the first 3-5 days. To reduce stress on the plant, you could remove all the flowers, and/or shade the plant temporarily by putting a trash barrel or something between it and the sun. Once it settles in a bit it will be fine.

When you removed the bush from the pot did all or some of the soil fall away? If so, tiny feeder roots fell away with the soil. These feeder roots are the only way the bush can take up moisture. Until they grow back, your bush will suffer stress.
Flowers take a lot of water. I'd remove the wilted buds to lessen the stress on the bush.
There is a way to plant a potted rose bush that won't cause stress. E-mail me for instructions.
Meanwhile do as hoovb said. Water deeply so it gets to the roots. A five minute sprinkling is not watering. Set your hose on trickle and let it run at the base of the bush for half an hour at least.