Hey Kumar,
We don’t have a direct download or trial version available— The best thing you can do is schedule a demo here: https://looker.com/demo and get a walkthrough of Looker. After that, you can get access to a free trial that you can hook your database up to.
If you really just want to take a look, you can play with our totally not business related game of thrones data in the embedded experience (this is not the complete Looker UI or experience):
https://play.looker.com/embed/dashboards/6