In a large saucepan, bring rhubarb, water and 1/2 cup sugar to a boil. Reduce heat; simmer, uncovered, for 6-8 minutes or until rhubarb is tender. Cool slightly. Set aside 1 cup rhubarb liquid for glaze. Place rhubarb and remaining liquid in a blender or food processor; cover and process until pureed.
Return to saucepan. Bring to a boil; stir in gelatin until dissolved. Stir in vanilla. Cover and chill for 1 hour or until slightly thickened.
Meanwhile, for glaze, combine reserved rhubarb liquid and remaining sugar in a small saucepan. Bring to a boil. In a small bowl, combine cornstarch and cold water until smooth; whisk into boiling mixture. Cook and stir until thickened. Remove from the heat. Stir in food coloring if desired. Cover and refrigerate overnight.
Gradually fold whipped cream into rhubarb mixture. Arrange 17 split ladyfingers on the bottom and 26 around the edge of an ungreased 9-in. springform pan. Spread half of the rhubarb mixture into pan. Arrange remaining ladyfingers over rhubarb mixture; carefully spread with remaining rhubarb mixture. Cover and chill overnight. Carefully spread glaze over top. Remove sides of pan. Garnish with strawberries and whipped cream.