May I know which is the best transport available from Shantou to Xiamen?

You have two choices, high-speed train and bus.
You can take a bus or taxi to Chaoshan Railway Station, where you can take the bullet train to Xiamen. The duration is about 80 mins.

Or you can take the bus from Passengers Coach Center (located No. 61 Taishan Road, near the railway station) to take the direct bus to Xiamen. The bus fare is about CNY120, and the travel time is about 3.5 hours.

Thanks Joe. What is the fare for the bullet train to Xiamen and is this bullet train available daily? Do you know the time of departure time to Xiamen.

The ticket fare of first class seat is CNY73.5 and second class seat is CNY61.5.
The bullet trains are available every day. Don't worry.
It takes around no more than 2 hours on the way.
The trains depart from 09:21 to 21:15.