In Nazi Germany (1933-1945), when prisoners were put into concentration camps, they were forced to wear a striped uniform. Each uniform had a number for identification and a colored triangle, which gave the reason for their imprisonment. According to The Holocaust Explained:
Criminals were marked with a green triangle, political prisoners with red, homosexuals with pink, whilst Jehovah's Witnesses wore a purple triangle and asocials (including Roma) wore a black triangle. In some camps, Jews were usually marked by a yellow triangle to form the Star of David. However, in others a yellow star identified them as being Jewish.
This color identification closely connects with Atwood's The Handmaid's Tale.
"...in their red shoes...The red gloves are lying on the bed...Everything except the wings around my face is red: the color of blood, which defines us. The skirt is ankle-length, full, gathered to a flat yoke that extends over the breasts, the sleeves are full. The white wings too are prescribed issue..." (Atwood 8).
"At the bottom of the stairs there's a hat-and-umbrella stand...There are several umbrellas in it: black, for the Commander, blue, for the Commander's Wife, and the one assigned to me, which is red" (Atwood 9).
"She's in her usual Martha's dress, which is dull green...The dress is much like mine in shape, long and concealing..." (Atwood 9).
In The Handmaid's Tale, the characters dress specifically to their role in the society of Gilead. The Commanders dress in all black, the Commanders' Wives in blue, the Handmaids in red, and the Marthas in green.
This close connection to what happened to prisoners in Nazi Germany would suggest that Atwood looked closely at, and included, past historical events to enhance her dystopian novel. Atwood used what happened in the past to hint at what could happen in the future if changes aren't made. It seems like her way of warning the reader about the consequences of history repeating itself.