The sauce will look marinara-like after simmering on the stove, but will lighten up to a browner color once the meatballs are baked in it. If you’d like a redder sauce that looks closer to the traditional tomato sauce, you can add extra beet juice (reserved from the can) a little at a time until the color is deeper. Please note that the more beet juice you add, the stronger the beet flavor will become. Personally, I prefer a less pretty color with less of the beet flavor, but the choice is yours!
You can also fry or bake the meatballs completely through, but separate from the sauce, then add them at the last minute to warm through and for the flavors to meld. That will yield a redder overall dish because the sauce won’t be diluted down by the extra liquid and fat that the Greek Baked Meatballs release as they cook.