Use the highlight feature to convey status. You can set the color of each item individually, or you can use workflows to set the color based on a status of a list item. See our knowledge base article, About model workflows.
For the highlight feature to work for the mini-grid layout, you need to use the Avatar/Icon/Images feature.
- Under the Highlight section, from the Color list, select the property to use to set the background color for the list item.
- From the Tooltip list, select the Free text property to use so that when a user places their mouse cursor over the highlight color in the grid view with avatars, they get some helpful information as to what the color indicates. Currently, tooltip support isn't available for other views yet.