In large saucepan, bring 1 quart (4 cups) water to a boil. Add sweet potatoes; return to a boil. Cook over medium heat for 8 to 12 minutes or until tender. Drain well. Return sweet potatoes to saucepan or place in serving bowl.
Meanwhile, in small bowl, combine syrup and cinnamon; mix well. Add to sweet potatoes; toss gently to coat. Just before serving, sprinkle with walnuts.