Jean Seberg is always ready for a swim in Bonjour Tristesse, and always in a different swimsuit. The red one brings out her girlishness, the blue one the color of her hair, the yellow one the tonalities of her skin. In fact, she rarely wears the same outfit twice throughout the movie; Mylène Demongeot, on the other hand, is intexricably linked to the few items of clothing her character is given: the blue-and-white dress, the ridiculous red swimming outfit she wears when she gets sunburned.
It's not quite as staggering a feat of customing as the 46 cheongsams Maggie Cheung wears over the course of In the Mood for Love (an average of one new dress every two minutes), but it has the same effect. If Wes Anderson in his movies teaches us to learn the character by learning their clothing, by seeing the same scarf or jacket just as often as we see their face or hear their voice (through "the clothes they are"), then Preminger and Wong want us to understand Seberg or Cheung not through the clothes they wear, but through the way they wear clothes. The thought is no longer "Man, that swimsuit looks good on her," but that swimsuits, whether yellow, red or blue, fit her so well to begin with.