Can a Party CAMO organization have a generic scope in its approval? For example, ‘sailboats’ without specifying specific models.

Yes, an organization with Part CAMO approval may have a generic scope on its approval certificate (AC-CAMO-P01-F14). However, even if the organisation approval has a generic scope, the continuing airworthiness management exposition (CAME) shall always reflect the specific scope of the organisation; It is therefore recommended that the generic scope of approval should not be excessively broad compared to the scope defined in the CAME.  
Organisations shall request from AESA any change to the scope defined in the approval certificate.