Upvote:3
There are several images of the layout on the Japanese Wikipedia page for Osaka Castle: https://ja.wikipedia.org/wiki/%E5%A4%A7%E5%9D%82%E5%9F%8E. In the grouping of three images on the right, the top left shows the castle under Toyotomi rule. The top right shows the layout in the "early Edo period."
https://upload.wikimedia.org/wikipedia/ja/b/b4/Oosakajou.PNG
There's also a website on the history of the castle with a page describing it during the Tokugawa period at http://www.osakacastle.net/history/haran/tokugawa.htm. You could run the page through Google Translate if you don't read Japanese.