Here’s a luggage sticker advertising the Southern Pacific/Rock Island Californian. As described in the brochure for that train, the Californian was a budget service designed to compete with the Union Pacific Challenger. The sticker was probably issued about the same time as the brochure, that is, 1938.
Like the image on the San Francisco Overland menu, the locomotive silhouetted on the sticker is somewhat generic looking, but it is obviously bigger than a 4-6-2 Pacific. Unlike the one on the menu, we can also see that it has a Vanderbilt (cylindrical) tender. Such tenders were found on Southern Pacific’s MT-1 Mountain locomotives but generally not on its GS-1 Northern locomotives, while Rock Island didn’t use them at all. So it seems likely that the image represents a Southern Pacific Mountain.