There’s a few things you could try. I managed to knock together a PoC using Bot UI: https://github.com/botui/botui/blob/master/README.md Also if you want something a bit more developed, you could look at https://github.com/sdelements/lets-chat
I managed to integrate the latter in a project I worked on a while back (please note the version of Rasa NLU is quite old) https://github.com/nmstoker/lockebot/blob/master/README.md#lets-chat