I'd like to know more about where this song comes from. It brings back a lot of happy memories for me.
In Carry It On which Pete Seeger wrote with Bob Reiser (1985), it says "this traditional Spanish song became the theme song of the United Farm Workers of America, led by Cesar Chavez"; and "the theme song of the most militant strike of the last quarter-century speaks only of the colors and sounds of the earth, which are everyone's birthright."
Here's the book's more literal translation:

In colors, in colors, the fields in the spring dress up.
In colors, in colors, the little birds come from far off.
In colors, in colors, the rainbow we see glistening;
And that's why those big many-colored loves are what I like.

The rooster, the rooster, sings with his cock--a-doodle-doo;
The hen, the hen, with cackle-a-cackle-a cackle-a-cack;
The chicks, the chicks, with their cheepy-cheepy-cheepy-cheepy-cheep.
And that's why those big many-colored loves are what I like.

Tune and complete Spanish lyrics are in the database here (click). Why it's listed as N-DE COLORES, I don't know.

I know first-hand the song was a favorite of the Cursillo Movement (that's where I learned it), and I'm sure many United Farm Workers leaders and members were cursillistas.
For those of you not interested in following the links, here's a brief description:

A Cursillo is a three-day learning, sharing, experience of living in a Christian community. The word "Cursillo" is Spanish, meaning "a short course". Cursillo is an abbreviation of the full title: 'Cursillo de Christiandad' which means, "A short course in Christian Living". During the three days of a Cursillo, a person not only hears inspiring talks on what it really means to be a Christian today, but actually experiences the joy of building and being part of a genuine Christian community. The Christian community formed during a Cursillo is very similar to the Christian communities in the early days of the Church.

And we sang, constantly - and told lots of dumb jokes. And yes, it was a good, moving experience.
-Joe Offer-