Caulfield Guineas is traditionally a day when the fashion takes a back seat to the group 1 racing but on Saturday, the style gave the four-legged stars a run for their money.

As fashion's first real test of what's to come for the spring carnival, racegoers took advantage of the mild weather and relatively relaxed dress code to experiment with bold prints and floaty silhouettes.

Jumpsuits and jewelled headbands were out in force among the ladies, while some gents experimented with jackets in lighter colours and fabrications – a promising sign there will be fewer business suits and more flair among men's looks this spring.

Leading the fashion pack were the over-35s, who were out early to have their photos taken for the Westfield Style Stakes, Caulfield's social media-age answer to traditional fashions on the field contests.

Rather than a catwalk, entrants' photos are judged by a panel, including fashion blogger Nadia Bartel, who looked as cool as ice in a soft blue Rebecca Vallance one-shouldered dress matched with a blue floral headpiece by Ford Millinery.

Bartel said she was looking for a point of difference and personality in the photos.

"Make sure the outfit is racing appropriate but has individual flair," she said.

Bartel said this spring was "all about mixing, the pinks and reds, the yellows and blues. I want to see different bold colours together. And I love all-red [outfits] this year."

Style stakes entrant Sharon Leigh Smith, 50, nailed the top-to-toe brief in an Alex Perry lilac lace dress, vintage silk coat and a headpiece she purchased online.

She said this was her third time entering fashions on the field but her first in Melbourne.

"I probably would have liked a catwalk but this is the way things are going now. It's easier for people to enter, it's more accessible," she said.

Ms Smith said having a 35-plus category was a welcome addition.

"Being an older woman it's quite hard to compete with beautiful young ladies," she said. "If you think you look good, don't worry about anyone else."

The Style Stakes, whose winners will be announced on Caulfield Cup day next Saturday, also includes a category for men, millinery and "squads" for groups of two to eight participants.

Given Caulfield's more relaxed vibe, there were plenty of characters on the course, including one man dressed in a green-and-yellow satin suit, and a buck's party group with the groom dressed in a colourful fascinator and "bride to be" sash.

Also mixing things up, albeit with more style, was stylist Lana Wilkinson, who stepped outside of her usual look in a Scanlan Theodore jumpsuit and "turband" (that is, a turban-style headband) by Christie Millinery.

Other celebrity guests at the Guineas included Neighbours star Olympia Valance, and models Ash Hart and Natalie Roser.