Happy Diwali Vector. Free vector template of postcard happy Diwali. Diwali, the festival of lights, is celebrated throughout India and symbolizes the victory of light over darkness, good over evil. Diwali, the festival of lights, is celebrated throughout India and symbolizes the victory of light over darkness, good over evil. On this day, with the coming of darkness and big cities and small villages of thousands of lights, illuminated with wicks floating in clay bowls, sparklers and fireworks..