In the best case scenario, you would prepare a diet for your cat which resembles closely the sorts of things cats eat in the wild: fresh meat, in the form of chicken or rabbit, including organs and fat, and very small amounts of grain.
Leaving Can Food
However, you may not have the time and inclination to do so, and there are some very acceptable alternatives in the form of premium brands of canned cat foods.
See my article on Canned Cat Food for more information on the virtues of canned vs dry foods for cats.
When to Leave Dry Food
On the other hand, if you have long working hours, and there is no one staying at home to feed the cats, you may also have to supplement with dry food left down for "grazing," during your absence. There are also automatic feeding devices, some of which have refrigerated units which are capable of opening cans with a built-in timer.
Be sure to provide plenty of fresh water for your cat when feeding dry foods. He will need the extra moisture he would normally get in canned food. Automatic water dispensers are excellent for this purpose.