The image sends on odd message for a CEO, regardless of gender, said Dan Schawbel, author of "Promote Yourself: The New Rules For Career Success" and the managing partner of Millennial Branding, a Gen Y research and consulting firm.
"It comes off as if she's on vacation, she's relaxing while everyone else is doing work," Schawbel said, noting it's especially bad since Mayer looks like she's reclining in her backyard and she famously banned employees from working from home.
(Read more: Working from home? Your boss may be spying on you)
The tablet device in her hand has a close-up image of her face, which Schawbel said may come off as narcissistic and fake. "On the picture in her iPad, she doesn't even look real," he said.
Schawbel said he was puzzled why she would pose for the picture. "I think a lot of people who are powerful just want the publicity. You're probably not going to see a male CEO turn downGQ. Maybe she's doing it because she wants to make Yahoo! look cool, with the iPad?"