public void setColor(final ColorRGBA color) {
        this.color = color;
        if (material != null) {
            material.setColor("Color", color);
        }
    }
sets the color

@param color the desired color (default=(1,1,1,1), alias created)
jme3-effects/src/main/java/com/jme3/post/filters/ColorOverlayFilter.java