For means there is a relationship, a benefit or inclusion between the two items. X for Y means that you have associated X with Y, and they should be used in conjunction.
There are so many valid uses of the word “for” and somehow this satisfies none of them.
If someone who loves and studies chocolate becomes, say, a bartender, and makes a cocktail specifically for the tastes of people who love chocolate in the same way they do, it is not unreasonable for them to advertise their cocktail as a "cocktail for chocolate lovers".
Will it be an appealing cocktail for all chocolate lovers? Conceivably not. Some may like more cocoa or some like a more buttery finish, some may be teetotalers and not want a cocktail at all -- but does that make it inaccurate advertising, or badly phrased? Not really, in my opinion.
This guy who loves the internet made a colour palette that he feels will be appreciated by those who love the same things about the internet as he does. Seems like reasonable and perfectly well formulated english to me.
When asked about the relationship between the color palette and the internet, his response failed to show any. He is not making an internet with colors, or colors with an internet, those are nonsensical statements. So in what sense is it for internet lovers? What characteristics of an “internet lover” would draw them to these colors?
When another commenter asked a similar question, his response was, “it’s not that deep”