General:
* Collection: This is the most common and versatile term, especially for a group of artwork gathered by a single person or institution.
* Exhibition: This term emphasizes the display of artwork, typically in a gallery or museum.
* Body of work: This emphasizes the totality of an artist's creative output.
More specific:
* Gallery: This is a good choice if you are referring to a group of paintings.
* Suite: This is often used for a set of prints, especially if they are numbered and limited.
* Portfolio: This refers to a collection of an artist's work, especially for a professional presentation.
* Ensemble: This term is more artistic and can be used for a group of diverse artworks that complement each other.
Ultimately, the best collective noun depends on the specific context and the type of artwork you are referring to.