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.
Click image to download a 143-KB PDF of this sticker.
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.