Combine first 4 ingredients in a large bowl. Stir together brown sugar and Worcestershire sauce until blended; pour over cereal mixture. Spray a 15- x 10-inch jellyroll pan with cooking spray; spread cereal mixture in a single layer in pan, stirring to coat.
Bake at 325° for 12 minutes, stirring every 5 minutes. Stir in graham crackers and raisins. Store in an airtight container.