Spray a rimmed baking sheet with the vegetable oil spray.
Combine the coconut and panko in a shallow dish.
Whisk the coconut milk, garlic powder, cumin, cayenne, and 1 teaspoon salt together in a bowl.
Add the cauliflower to the coconut milk mixture and toss to coat well.
Working with 1 piece of cauliflower at a time, remove from the coconut milk, letting excess drip back into bowl, then coat well with coconut-panko mixture, pressing gently to adhere; transfer to the prepared sheet.
Bake until the cauliflower is tender, golden, and crisp, 20 to 25 minutes, flipping the cauliflower and rotating the sheet halfway through baking.