While there is no official map of Diagon Alley, the books describe some of the shops in a general relationship to each other. Using this information, I created the following map in 2001 (before OP). The most important shop not included is Weasley’s Wizard Wheezes which didn’t appear until book six. Fred and George’s establishment would appear farther down the high street, past where my map ends. –SVA

In Pottermore, the Alley is a lot shorter than I drew it, with far fewer shops. However, they only needed to include the shops a user to the site might actually visit (as part of the Pottermore “game” experience). Therefore the canonicity of the order is questionable. Here’s how it appeared on Pottermore: