Is this good to eat ?

Hello, I just harvested the only sweet potato from my crop (but it was a first! I just buried an old sweet potato in my garden). To be more precise with my question : earlier this year, I planted an orange-colored sweet potato. But I was surprised when I dug up the “harvest” today : the sweet potato is dark purple! I don't know anything about this… Is this normal (I suppose)? More importantly, is it safe to eat or could it be toxic?

Thank you for your expert advices!