I don't see how pasta can be kept warm without it getting pretty gummy and unpleasant, especially without sauce.
Why don't you consider some baked pastas, that are intended to be warmed?
Timballo is a baked pasta dish using rigatoni or ziti, tomato sauce, little meatballs, peas, boiled eggs, mozzarella, grated cheese. You can fry some eggplant slices and layer them in it or line the baking dish with them and then they;re baked.
You could make several ready for the oven and then put them in one at a time, so that you take them out as they get finished in the buffet
You could do an Italian macaroni and cheese - again pasta like rigatoni work well, mix with several types of cheese, ricotta, parmigiano, and whatever you like, mozzarella, caciocavallo, fontina, etc. Salt and pepper to taste, bake in a buttered baking dish coated with breadcrumbs, breadcrumbs and dotted with butter on top
Or make it with a bechamel and add the cheeses to it, if you want something creamy.
And a lasagne dish.
Three pastas, put all three in oven at once, and have other trays ready to go in the oven, as one is half done, add another, pull the first out when it's done and then add another. Then the pasta is always hot.
Or else do as they do in restaurants, cook the pasta almost (with a thin white line still inside when you bite it) and put immediately into cold water. When it's time to put it out, dump it in boiling water for a moment to heat it through, then into the sauce and bring it out.
For the baked pastas, make sure to cook the pasta underdone (it should be a little less done than the hot water method - the white line in the center when you bite into one should be more noticeable, but not crunchy) or it will be overcooked when it's baked
You could also do a cold pasta - like with fresh tomato and mozzarella tossed with oil and the hot pasta added to it when it's cooked.
But I think having pasta staying heated and without sauce is not going to be a very pleasant meal. Pasta should be boiled and sauced immediately and eaten or it feels like eating at the cafeteria at school