It appears to be from Batman #203, from August 1968:
- If you’re reading this, you’re probably familiar with the feature, but to recap, Secrets of the Batcave — 1968 is four pages, including a two-page splash of Wayne Manor and the Batcave, a page the explains the intracacies of Batman and Robin’s utility belts and a page on various other equipment, including the Batarang and Batplane. Batman #203 was an issue filled with reprints spotlighting various aspects of Batman’s arsenal.
(source: 13 QUICK THOUGHTS on the Glorious SECRETS OF THE BATCAVE — 1968, from 13th Dimension)
More info, including the full map, is available at the 13th Dimension link above.
(Process: I did a reverse image search of the blueprint image from the question, found a few references that narrowed it down to "a 1968 Batman comic", and then searched for "batcave 1968 diagram", which led to relevant results.)