Hi Neha thanks for posting on the community! 

While there isn't a way to automatically highlight the tables connected to a particular table in your ERD you can manually adjust the style of each table from the properties bar as explained in the Add Style section of the ERD article.

If you prefer you could instead set up Conditional Formatting rules to style specific shapes based off of the shape data or the text they contain etc. Details and instructions on setting up Conditional Formatting rules can be found in the Conditional Formatting and Icon Sets article. Please note that this will require setting up rules based off of what is contained in the tables you are highlighting so this still isn't a way to automatically style all the shapes attached to a particular shape.

If you would like to pass on your idea would you please add it to our feature request form? Ideas submitted here are passed onto our product development team for their consideration. Thanks!