An anthill is technically either a formicatrix or a formicetum, and the colony or community of ants is the formicarium. However, in this situation we want to use colloquial or poetic terms, not technical terms. The common person's word for an anthill in general is the caverna formicosa and for the hillock of the anthill, the word grumulus is used. The poetic word for a hive is alvus or alveus, however, this word is more used for the structure of the hive, not the insect community. I think the use of the word nidus is ok in this context, but we could also use alveus, but grumulus would be my choice for something homey and motto-like.
Concerning work, you would not use the word laboro, because this implies brute or menial labor. When Romans talk about working hard, they use the word contendo. So, you can say labore contendit.
Concerning the advantage to the nest, the typical word, especially for an animal would be commoditas. However, when we talk about an animal working for the benefit of something, it would be better to use the expression opere efficior. So, altogether, this how I would say it to convey a homespun or moralistic tone:
Formica ad usum grumuli opere efficitur.
Concerning your proposed rendering (laborat formica ad bonum coloniae)... You could certainly write this and a Roman would know what you meant, but it would sound very awkward and barbaric. Kind of like the way Borat says "Make benefit glorious nation of Kazakhstan!" We know what he means, but we can tell he is a foreigner just translating foreign expressions into English word for word.
First laboro means to toil like a slave or prisoner. You would not normally use that word for a citizen. It does not have a positive connotation. Romans did not have the same kind of work ethic that Americans do. Secondly, ad is a preposition of position or motion. You would say pro bono for benefitting someone, as in pro bono publico (for the public good). However, this expression is used for people, not animals. People have bonum, animals have usum. The use of the word coloniae is ok as you have it.