I think that you need one style for each color. A style in Word, is simply a collection of characteristics that are applied all at once, with a mouse click or a keyboard shortcut.
In this case, it will be a character style, rather than a paragraph style, since the latter applies to an entire paragraph and your need is for only some of the text in each line (paragraph).
Look up creating a character style in Word. The simplest way in your case, I think, will be to first select one or more letters of, say, the red text. When you open the new style dialogue, the character formats will already be recorded in the box. You give the style a name and save it. Do the same for the other colors of text you want.
The style can then be applied in a number of ways. Look up applying styles in Word.
If you need further assistance, please reply.