Princess Daisy has always been shown with an affinity for a yellow-orange color since her debut in Super Mario Land. While her in game sprite was black and white, her character artwork depicted on the boxart showed that Daisy had orange, long luscious locks of hair, as well as a yellow dress. Daisy would later appear in Mario Party titles, where characters were 'assigned' a unique color when they would use a candy, orb, or other special item on a space. Perhaps the most evident and concrete connection of Daisy to the color orange is from the Mario Kart series, most notably in Mario Kart 8.
The Princess of Oranges?
Mario Kart 8 introduced a new brand named "Princess ORANGE", which can be seen as a sponsor along many tracks. The brand also appears on multiple vehicles, such as the Circuit Special and Sport Bike, most often on female character's as well as some of Donkey Kong's motorbikes. In addition to the words "Princess ORANGE", the design features Daisy's emblem on top of an orange, clearly illustrating that this brand has a connection to her in some manner.
While not directly stated, the brand Princess ORANGE also appears on bottles of soda, as depicted in Sweet Sweet Canyon, which is what racers drive in during the "underwater" portion of the track. Whether Princess ORANGE is an umbrella term that applies to vehicles, soda, and other material, or if Princess ORANGE is a soda brand being advertised on vehicles and tracks is unclear and up to opinion.
☀ Although the connection is unknown, the Princess ORANGE sponsor is most likely paid for by Daisy herself to advertise the brand and/or soda, as sponsors are typically paid for the person in charge of them.