Senior director of procurement is a multifaceted position needing a multifaceted skill set. Internally, you will be creating the strategy for your department that will allow them to work effectively and collaboratively with all other departments that will require procurement. On the other hand, you will be dealing directly with vendors, especially on significant purchases.
You, therefore, need to emphasize your successes with negotiating and dealing with vendors, as well as your skills and successes at leading a team and positively affecting strategy. The following does both very effectively.