A complete technical reference of the Junkers Ju 388 was never made. Unfortunately, I know of no surviving manufacturer's plans, either. Yet, the manual provides quite a lot of magnificent drawings. Let's start with a side view of the Ju 388.
On the same manual page, there's this view from above:
As can be seen from these maintenance plans, the landing gear was directly taken from the Junkers Ju 88.
Last but not least, there's a section from the original Junkers Drawing S 38800-9094a, which shows a side view of the cockpit and part of the fuselage. It was scanned from NASM microfilm R 2016 using a Minolta Dimâge Scan Elite F-2900.