What is the white sauce of Domino's pasta made of?
It's Alfredo sauce and according to Domino's nutrition guide it's made of:


  Water
  Cream (Cream, Milk)
  Parmesan Cheese (Part-Skim Milk, Cheese Cultures, Salt, Enzymes)
  Asiago Cheese (Pasteurized
  Milk, Cheese Culture, Salt, Enzymes)
  Margarine (Palm Oil, Water, Salt, Vegetable Monoglycerides, Whey Solids,Sodium
  Benzoate [Preservative], Natural And Artificial Flavor, Citric Acid, Beta Carotene [Color], Vitamin A Palmitate Added)
  Seasoning
  (Maltodextrin, Nonfat Milk, Modified Corn Starch, Salt, Enriched Bleached Wheat Flour [Bleached Wheat Flour, Malted Barley
  Flour, Niacin, Reduced Iron, Thiamine Mononitrate, Riboflavin, Folic Acid], Disodium Inosinate, Disodium Guanylate, Xanthan
  Gum, Spices, Mono And Diglycerides)
  Butter (Butter, Salt)
  Parmesan Cheese Concentrate (Parmesan Cheese [Pasteurized
  Milk, Cultures, Salt, Enzymes], Water, Salt, Natural Flavors, Yeast Extract, Sodium Phosphates, Sodium Citrate)
  Modified Corn Starch
  Garlic (Garlic, Water)
  Chicken Base (Chicken Meat, Chicken Juices, Salt, Potato Flour, Flavorings, Sugar, Disodium
  Inosinate, Disodium Guanylate)
  Parsley
  Salt


You can definitely make something similar at home. You should also be able to buy something like it in a jar at your local grocery store.