Defensive errors proved costly for Leeds as they gifted the League leaders all three of their first-half goals.
England winger Yankey hit the opener before Sanderson bagged a brace to take her season's goal tally to 31 in all competitions.
The second half was more evenly contested, but the home side were caught on the break by Scotland striker Julie Fleeting to head in the final goal.
Victory took the Gunners seven points clear at the top of the table, with Arsenal having four games in hand on second-placed Bristol Academy, who had no weekend fixture.