Granata's surviving solo works have been transcribed in Gary R. Boye's 1995 dissertation "Giovanni Battista Granata and the Development of Printed Music for the Guitar in Seventeenth-Century Italy". A PDF download of it costs $42 (in America) from: http://www.umi.com/en-US/products/dissertations/disexpress.shtml
Boye's transcription and parallel tablature are handwritten.
Granata's Op. 3 "Sinfonia a dui" is transcribed (65 measures long), but I don't see any "sonata" listed in Boye's inventory of "Nuova Scielta" (1651).
Yes, I do see it there, too. It is a "sonata", I suppose, in the sense that it is a piece to be played by instruments. Granata does use the term for his Op. 4 piece for guitar, violin, and basso continuo.
Are you playing any of the other pieces for guitar and continuo? -- R