Granson Lew, Williams's Doll, and Over and Over needs no introduction. Neither does her collaborator Maurice Sendak, who has illustrated so many of today's best-loved, as well as most distinguised, books for children. The heroine of their book has a problem. And at first it does not look as though Mr. Rabbit is going to be much help in solving it . For everyone knows you cannot give your mother a red roof, a yellow taxi-cab, a green caterpillar, or a blue lake for her birthday. But then all the little girl had said was that her mother liked red, yellow, green and blue -- and so Mr. Rabbit was trying.How he and the liitle girl come up with the absolutely perfect present makes a story the the youngest reader will love. And the wonderously bright full-color pictures will bring hours of pleasure to readers and lookers of all ages.