The Quantum Alternating Operator Ansatz (QAOA) is a promising gate-model meta-heuristic for combinatorial optimization. Applying the algorithm to problems with constraints presents an implementation challenge for near-term quantum resources. This work explores strategies for enforcing hard constraints by using XY -Hamiltonians as mixing operators (mixers). Despite the complexity of simulating the XY model, we demonstrate that for problems represented through one-hot-encoding, certain classes of the mixer Hamiltonian can be implemented without Trotter error in depth O(κ) where κ is the number of assignable colors. We also specify general strategies for implementing QAOA circuits on all-to-all connected hardware graphs and linearly connected hardware graphs inspired by fermionic simulation techniques. Performance is validated on graph coloring problems that are known to be challenging for a given classical algorithm. The general strategy of using XY mixers is borne out numerically, demonstrating a significant improvement over the general X-mixer, and moreover the generalized W -state yields better performance than easier-to-generate classical initial states when XY mixers are used.