There is a question in the Question and Answer Group that you may wish to look at as the responses provide additional insights. For instance, the black and white oppose each other as symbols that underscore the paradox of the play: "Fair is foul, and foul is fair."
Interestingly, white is suggestive of cowardice and weakness as Lady Macbeth berates her husband for having "the milk of human kindness" and Lady Macbeth chides Macbeth again:
My hands are of your color; but, I shame
To wear a heart so white.
And, in Act I, Scene 7, Lady Macbeth uses green to symbolize Macbeth's cowardly behavior. In addition, silver and gold are used to allude to King Duncan.
Blood and red are symbols which act as a recurring motif, especially when contrasted against white. For example Lady Macbeth states that she "shame[s] to have a heart so white" when she does not physically kill Duncan herself. The image of red as "tainted" against "white" as purity also is found as Lady Macbeth is washing the proverbial blood off of her white hands as she dreams.
Consider how color is used to promote the theme embodied in "fair is foul and foul is fair." I guess this is more metaphorical, but the light of favor which seems to be surrounding Macbeth at the beginning of the play is actually hiding the darkness of his heart and his unchecked ambition. Lady Macbeth, a woman and therefore presumed virtuous and welcoming, is actually venomous and murderous. This constant light/dark motif is connected, I think, to the darkness of the play. Remember that Shakespeare's stage was lit only by natural light, so any references to darkness had to be emphasized because the natural environment of the play wasn't particularly dark. Even the blood--of which there is much in this play--rarely shows up on stage. Most is offstage action brought onto the stage. It's the words which first indicate the darkness, the blackness of the play, followed by the characters and their actions.
drmonica is right in drawing attention to the bleakness and darkness of most set designs and productions of this play. The Polanski version is a case in point - I love the part where they meet the witches first off on the moor during a windy, Scottish storm. Of course, the bleakness of the setting is a kind of pathetic fallacy that foreshadows the bleakness of the rest of the play. I agree with #2 in that colour is not necessarily used, but blood is definitely referred to implicitly and directly throughout the play for the reasons stated.
Usually the set for productions of Macbeth is very dark and the characters are dressed in black. You are correct that blood is a motif in the play. Blood is referenced in the murders ordered and committed by Macbeth and his wife, in the military battles that are fought, evoking violence.
Blood is also a reference in the familial lines present in the play. Macbeth has no right by blood to sit on the throne, while Duncan's sons have the blood birthright. Macbeth orders the murders of Macduff's family (blood). Lady Macbeth imagines that she sees blood on her hands and cannot wash it off. I'm not so sure that color is the reference, but blood certainly causes one to "see red."
There is a great deal of color used in the play, mostly of white, green, and black. The most predominant are white and green which refer to people and places and events in the play. I am not sure the color red shows up that much.