I do cake decorating as a side business.
Your cake will be fine either in the fridge or frozen. If you baked it today and don't want to freeze it, you need to frost it and that will keep it moist. If frosting is not an option, you need to wrap it in saran wrap, tightly with no chance of air getting in. If it will fit, putting it in a ziplock bag is an option. Being wrapped in tin foil allows in too much air and it will dry out.
Keep in mind that simply refrigerating or frosting it won't give it too much of a shelf life after you eat it Monday. Any leftover will need to be eaten quickly or tossed.
Freezing is a good choice too. Some people are against frozen cakes, but almost every cake purchased from a chain store bakery arrived frozen. After it is cooled completely, seal in saran wrap and place in the freezer. Be careful not to put it where it will get crushed or freeze unevenly. On the occasion I have had to freeze cakes, I wrap it and then place the wrapped cake back in the pan and then freeze. The pan helps keep it safe.