Need to place custom conversational button in Embedded messaging chat window welcome screen.

Hi Trailblazers, 

Need help to achieve a requirement where I need to put some custom conversational button on embedded messaging chat for service type of agent. So when I click predefine text button on chat window, it should send as a message so that user should not need to type. 

It's a similar like what we have on 'Ask Agentforce' on trailhead. see image below.