The One With Rachel's Inadvertent Kiss - S5-E17
Trivia: When viewing this episode on DVD compared to viewing it on Netflix, not only are a few shots deleted on the Netflix version, but there are also shots which had been filmed differently when Rachel returns after her first interview. On the DVD, she walks over to the table, puts her briefcase down on the chair and walks to the fridge, takes out a bottle of water...and then in a closeup Chandler asks her what happened while he's holding the newspaper. But in the Netflix version, Rachel walks over to the table, and just as she puts her briefcase down on the chair she stands behind the chair, and Chandler asks her what happened - all in the same wideshot, with the newspaper lying on the table.
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.