Because of the enormity and global nature of WW II, minorities were involved in a number of ways. As mentioned, women entered the work force since the men were in uniform.
Perhaps the best example of the contribution of Native Americans were the code talkers. The most famous code talkers were Navajo although native men from other tribes were also involved. Since these men were speaking in their native languages, they were able to communicate without fear of being understood by the listening enemy.
Unfortunately, African American soldiers for the most part, were not used as effectively. Rather than integrate them into combat units, they were often used as "unskilled" labor, ie loading supplies or burying the dead.
At the end of the war, the face of the labor force in America changed greatly. The seeds had been sown for the economic growth of the 50s and the various civil rights movements which began to gain momentum in the 60s and continues to this day.
At the beginning of the 20th century minorities were treated as second class citizens.
For example, women were brainwashed into believing that their role was in the home. If they did have to work, it was girls are nurses and boys are doctors or women are secretaries, not bosses, etc. WW II changed all that and the role of women changed.
The doctrine of separate but equal ruled African American education. The races were definitely separate but were not, for the most part, equal. School districts were carefully gerrymandered to keep all the minorities in the same schools. White students attended white schools and black students attended black schools. Black schools, especially in the south were given the cast off books and other materials from white schools. The Civil rights movement and integration changed all that.
For many Native Americans, it was back to the reservation although some escaped via the G.I. Bill. As the country looked at itself internally with the emergence of the Hippies, a new pride for native people was born with the rebirth of their culture. Groups like AIM put a light on the plight of the native people in this country. More Americans became aware of pre-European American and the contributions of the native people. Since the various treaties made with numerous tribes of people recognise them as nations, reservation are sovereign. In a sense, Native Americans are dual citizens. Although many tribes support themselves with the "new buffalo", gambling, and have become rich, other tribes live in extreme poverty. Progress has been made for Native Americans but more is necessary.
One must admit that WW II changed American for the better. By the beginning of the 21st century, minorities had gained rights denied their relatives in the 20th century.