Ok, clearly Gwen Stefani does not age.

That's all we can say after seeing the fashion chameleon on the cover of InStyle's April issue and the inside spread.

On the front of the magazine the 40-year-old star shines in a crinkly blue deep-V Stella McCartney top with voluminous shoulders, while inside she's a mix of high glam (in gowns by Lanvin and Louis Vuitton) and signature Stefani, Queen of Ska, in a white tank top, black leather fingerless gloves and her trademark tousled platinum locks.

"I feel really lucky that someone wants to put me on their cover," a modest Stefani says in this behind-the-scenes clip of the shoot, where she's seen posing in a short multi-colored Louis Vuitton cocktail frock, which she says is her favorite outfit, and wears dark film noir makeup.

"Style is just something that comes from within you," she says in the clip."The funny thing about style is I don't really like to talk about it, I like to just do it. I love designing clothes and I love to wear them. Every opportunity I can, which is pretty much every day of my life, I like to get dressed up. It's just something I've done every since I can remember."

And while dressing up is one of her favorite things to do, she says that shopping is not. So instead she gets her stylist Andrea Lieberman and her team to pull looks for her.

"They do the edit for me, then I edit that," she says. "It's very luxurious . It's one of the perks of the job. But it's not a job, it's my life."

In the accompanying article, Stefani dishes on why she stepped away from music and decided to become a fashion designer with her L.A.M.B. label and create a fragrance, among other things.

"I wanted so badly to have a backup plan for when I'm not performing anymore," she tells the magazine. "Let's be realistic: it's not going to be like this forever. So I wanted to continue having something creative to do."

"I have to be creative to be happy," says the workaholic mother of Kingston, almost four, and Zuma, 1 1/2. "I don't have a strong sense of self-worth unless I'm doing something. I was a different person before I started to write. When I realized I could be a songwriter and that people would listen -- that was when I started feeling good in my life."

To read more of Stefani's interview and see more images from her shoot, head over to InStyle.com and pick up the April issue on newsstands March 19.

In the meantime, read what Stefani told StyleList recently about her brand new, leather-heavy Fall 2010 collection and see which reality star wants to follow in Stefani's celeb designer footsteps.