如何更改Cocos2d MenuItem的颜色？

#include "cocos2d.h"

USING_NS_CC;

class MyScene : public cocos2d::Scene
{
public:
    static cocos2d::Scene* createScene();

    virtual bool init();

    CREATE_FUNC(MyScene);

private:
    MenuItem* createMenuItemWithColor(const std::string& text, const Color3B& color);
};

USING_NS_CC;

Scene* MyScene::createScene()
{
    auto scene = Scene::create();
    auto layer = MyScene::create();
    scene->addChild(layer);
    return scene;
}

bool MyScene::init()
{
    if ( !Layer::init() )
    {
        return false;
    }

    auto menu = Menu::create();
    menu->setPosition(Vec2::ZERO);
    this->addChild(menu);

    auto redMenuItem = createMenuItemWithColor("Red", Color3B(255, 0, 0));
    auto greenMenuItem = createMenuItemWithColor("Green", Color3B(0, 255, 0));
    auto blueMenuItem = createMenuItemWithColor("Blue", Color3B(0, 0, 255));

    menu->addChild(redMenuItem);
    menu->addChild(greenMenuItem);
    menu->addChild(blueMenuItem);

    return true;
}

MenuItem* MyScene::createMenuItemWithColor(const std::string& text, const Color3B& color)
{
    auto normalImage = Sprite::create("menu_item_normal.png");
    auto selectedImage = Sprite::create("menu_item_selected.png");

    normalImage->setColor(color);
    selectedImage->setColor(color);

    auto menuItem = MenuItemSprite::create(normalImage, selectedImage, [](Ref* sender) {
        CCLOG("MenuItem clicked!");
    });

    menuItem->setNormalImage(normalImage);
    menuItem->setSelectedImage(selectedImage);

    return menuItem;
}