The dog needs to be taught to sit when the cat is near. You can do this by putting a leash on the dog. Lead him near the cat, tell him to sit, help him into the sitting position, praise, treat.
Leave the leash on the dog for awhile, and if the cat is near do this a few more times. If the dog barks at or runs at the cat, pill quickly on the leash, saying "NO, sit", and make the dog sit.
Other times even if you don't have the leash on the dog, do the same training, but use the dog's collar to help him into the sitting position.
Since the dog may be a little rowdy, and will take time to learn, also get a dog cage. Put the dog in the cage for brief periods during the day, in order to allow the cat to come out and have a little freedom in her own home. This also helps the dog to see the cat as somewhat superior.
Continue with training until the dog understands. If the dog is too rowdy, put in the cage for a little quiet time. Also take the dog on walks to reduce energy level.