I've been thinking that the preference for a wider variety and greater vibrancy of colors during dangerous times is a lot more general than clothing (see below for that). For example, cars used to look fairly dull in coloring from the mid-'30s through the late '50s. It wasn't until the '60s that cars turned yellow, lime green, baby blue, etc. I remember that lasting through the '80s. Then the '90s and 2000s ate the cars' colors and by now they're all silver / gray, white, black, and a handful of red or blue.
But cars would go under the broader class of "public signals," so maybe during dangerous times people want to send more colorful signals either to intimidate others or to help their courtship effort. What about private signals, where neither of these would apply? If we can find lots of those examples, that suggests that it's a deeper preference for colors that develops during rising-crime times, not just a showboating behavior in public.
How about cereal? Few in your non-kin social circle are going to see how colorful your cereal is, so it's a fairly private signal. I remember as a child in the 1980s that every other breakfast cereal was exploding in color, both in variety and intensity. It was a real treat to look at, especially when it turned your milk that color and you got to drink purple milk -- something not available for purchase in stores. In fact, the kaleidoscope of colors was often a key selling point in the advertising, as in the TV commercial for Rainbow Brite cereal (one that I never ate, but whose ads I still remember).
I looked over the cereal aisle at the local mega-market today, and I could only count about 6 or 7 brands that were pretty colorful (Trix, Lucky Charms), and maybe one or two others that had a little color but either not a wide variety or high intensity (Apple Jacks). Everything else is some shade of beige or brown, perhaps with white if there's frosting.
With the exception of Alien cereal, we had all of these cereals in the '80s (a trend that began sometime in the '60s or the '70s at the latest). Just to list some that were pretty colorful but no longer exist: Fruity Marshmellow Krispies, Smurfberry Crunch, Nerds, Circus Fun, Ghostbusters, Franken Berry, Boo Berry, and Yummy Mummy (all three were part of a horror movie themed line; only the bland-colored Count Chocula has survived), Teenage Mutant Ninja Turtles, Pac-Man, Strawberry Shortcake... and probably a lot more.
These were not all available in all years -- in any given year, maybe 3 or 4 would have been in production. But still, cereal used to have a much wider variety and intensity of colors.
It's even stranger since there has been a huge shift away from obviously sugary food for kids, and that has involved making everything "fruity." That way it's still loaded with sugar, but the parents feel less guilt because Fruity Pebbles has a more natural feel than Ice Cream Cones (a real cereal back in the '80s). You'd think this would have resulted in a lot more fruit-themed cereals, and so an even greater explosion of color. But it has gone the other way.
Other ideas for private signals of color preferences? Ideally you only consume them in private (or close to that), and they shouldn't be very durable -- not furniture, for example, since any guest you ever have will see what color your chairs and blankets are, but probably not how colorful your breakfast cereal is. Band-aids, maybe? I remember when they used to come in bright, multicolored varieties, and not just the ones aimed at kids, but also adolescents or adults who liked wearing neon clothing and accessories.