making sweet potato casserole. Need to make it orange!!
You could dye them I suppose, but they're vastly different in taste aand other characteristics- I'd go back to the store.
Unless you really need them to be orange in color, white sweet potatoes can make a darn fine sweet potato casserole too! If you're more concerned about the color, though, you could add some mashed carrot, butternut squash, or pumpkin.
No hope on the color unless you call Harry Potter for a magic spell.
They still taste good!