Complex sentence: Parisian society compared Germaine de Staël and Mme Raguet to Minerva and Juno and named their garments for Roman deities: gowns were styled Flora or Diana, and tunics were styled "à la" Ceres or Minerva.
Split into simpler sentences: Parisian society compared Germaine de Staël and Mme Raguet to Minerva and Juno and named their garments for Roman deities. Gowns were in the style of Flora or in the manner of Diana, and tunics were styled "à la" Ceres or Minerva.