Well, Here's the version that's in "Singing the Living Tradition" (the current Unitarian-Universalist Hymnal in the US). Personally, I like Arkin's lyrics a lot, even though (as Garrison Keillor might attest) I wouldn't put it past my fellow U-Us to use the original Spanish song, poultry verses and all, as the anthem for a Sunday morning service.
I always include this version in programs I do for Martin Luther King Day.
Genie

De Colores
(Traditional Spanish Folksong; English Words: David Arkin © 1992

De colores, de colores se visten los campos en la primavera.

De colores, de colores son los pajaritos que vienen de afuera.

De colores, de colores es el arco iris que vemos lucir

Y por eso los grandes amores de muchos colores me gustan a mí.

All the colors, 
All the colors we see in the springtime with all of its flowers.

All the colors, 
When the sunlight shines out through a rift in the cloud & it showers.

All the colors, 
As a rainbow appears when a storm cloud is touched by the sun.

All the colors abound for the whole world around

And for everyone under the sun.

All the colors,
Yes the colors of people parading on by with their banners.
All the colors,
Yes, the colors of pennants & steamers & plumes & bandanas.
All the colors,
yes the colors of people now taking their place in the sun.
All the colors abound for the whole world around
And for everyone under the sun.

All the colors,
Yes the black & the white & the red & the brown and the yellow.
All the colors,
All the colors of people who smile & shake hands and say, "Hello!"
All the colors,
Yes, the colors of people who know that their freedom is won.
All the colors abound for the whole world around
And for everyone under the sun.