Celebrating festivals at the office is a nice concept to bring people closer and enhance the culture of the organization. You can first create a cultural group with members who can help you out and are innovative. List some events to be done on the day, ask someone to perform, or arrange your local food items to be served on the day. You can arrange them from the market but do count your attendees. Draft an email and send it to members while also fixing it on the notice board. Invite all your employees to gather in an art hall or any room you can arrange. Also, invite your business/cultural/PR head as a guest. Have some cultural programs arranged for it, prizes for distribution, and games too. This way, you can easily let people interact in a nice manner. At the closing, you can gift all members foodies famous for the festival and close the program by wishing them for the day.
Hope my suggestions will work for you.
Regards,
Arvi