There is hereby established, within and as a part of the department of revenue, a division of taxation, the head of which shall be the director of taxation. Under the supervision of the secretary of revenue, the director of taxation shall administer the division of taxation. The secretary of revenue shall appoint the director of taxation, and the director shall serve at the pleasure of the secretary of revenue. The director of taxation shall be in the unclassified service and shall receive an annual salary fixed by the secretary of revenue and approved by the governor.