Magazine images courtesy of Major Pepperidge via Gorillas Don't Blog.
A similar photo, one that clearly originated from the same shoot, was used on a 1965 trading card. The card set was produced by Donruss (see earlier Archive entry). It's quite similar to the magazine cover yet different, including the addition of another young guest. And we can see the card image was also printed in reverse.
The only mention of Snow White inside the 1961 magazine is in the article, "The Happiest Show on Earth--Disney Cartoon Stars to Make Daily Appearances" (p.5). It reads:
Disney artisans have been busy as the Seven Dwarfs since the first of the year, creating - among numerous other show-stoppers - - the Seven Dwarfs themselves! (Along with Snow White, they're featured on the front cover of this VACATIONLAND issue.)
In the spring 1974 issue, Snow White would again be featured on the magazine cover, this time with a young park guest in front of the Grotto statues. There doesn't appear to be any mention of the princess inside, though.