an English sentence

It isn't clear what you want here. However, "one of all, all of one" makes little sense.

I'm finding a sentence that can describe a large group of people who work together and help each other

Well, this sentence is an English translation from Latin of the motto Unus pro omnibus, omnes pro uno.

The phrase means One for all, all for one in English. It is known as being the motto of Alexandre Dumas' Three Musketeers and is also the traditional motto of Switzerland.

Note that this shouldn't be mistaken for "Et pluribus unum", which is in the seal of the United States and means "Out of many, one".

Francis has your answer.