Head to the advanced search page and click the 'Saved searches' tab. 

Click 'Edit' on any existing featured search

Change the layout type to 'Masonry' and select the maximum number of images you want to display in the layout and press the save button.

Return to the homepage to see the results.
 

How do I create a new masonry saved search?

Whenever you are on the search results page you can click 'Save this search' in the top right hand corner:

Add a name for your search, set the type to 'Featured' and the layout type to 'Masonry' and hit save.

 
Now if you return to the homepage you will see your saved search on display.