This is a take on Woman with a Parasol, turned to the left by painter Claude Monet. Although in this version the woman has pink hair - possibly referring to Junko Enoshima or Kotoko Utsugi.
I'd say it's more likely to be Junko because:
Firstly the hair length is similar to Junkos, Also Jataro confesses to Komaru and Toko that Junko was the only person who had ever shown him affection and love. It's also implied he has a childlike crush on her.
The original painting is of Alice Hoschedé
who was later to become Monet's wife. Possibly a desire of Jotaro's brought out in his painting.
She was one of Monet's favourite models.