Exactly as Craig has said. If you are interested in her early fit, with the stern tubes, photos show the opening well enough. If interested in the later fit, I have found this:

https://www.ussleahy.com/Janes_79-80_1f.jpg

Page 688 from 1975-1976 edition, from this list here:

http://www.ussleahy.com/Janes.html

The text at the bottom left of the page reads:

"Torpedoes: Fixed Mk 32 tubes are below 3 in gun mounts, built into superstructure."

And, if you enlarge this image, you will see they painted a nice red vertical warning rectangle around the two tubes under the aft part of the midship tub. The tubes are circular, stacked one over the other, with the bottom tube being in more sun, so clearer:

https://upload.wikimedia.org/wikipedia/commons/f/f3/USS_Truxtun_%28CGN-35%29_underway_in_the_Pacific_Ocean_off_San_Diego_%28USA%29_on_3_January_1989_%286450111%29.jpg

I have not looked into the date when this switch from stern to superstructure occurred, but the stern system as a whole did not last very long. The majority of her service would likely be with these tubes under the gun tubs (later Harpoon tubs) within the superstructure.