Combine 0.75 cup of sugar, cornstarch and water in saucepan, stirring until cornstarch is dissolved. Finely chop or crush three of the peaches. Add these to cornstarch mixture. Blend in food coloring. Bring to boiling point, reduce heat and simmer until mixture is thick and clear. Stir it constantly during the cooking period. Cool. Slice remaining peaches, arrange them on bottom of baked pie shell. Sprinkle with about 0.25th cup of sugar. (If peaches are very sweet, less sugar may be used.) Spoon cooked mixture onto sliced peaches. Refrigerate for several hours before serving. Top with whipped cream or vanilla ice cream, if desired.