If you click on your bot, the URL in your browser will be your bot's URL, you can book mark or link to this. You can also get this URL from your bot's Details tabs.
If you want a link that goes straight into chatting with the bot you can set a "subdomain" in your bot's Edit Details setting to have your own subdomain for the bot. You can also click on Chat which gives you a URL like,
https://www.botlibre.com/bot?instance=12345&dynamicChat=Chat
