This does not depend on jqGrid, instead that you can color all the elements of the grid using jqgrid bootstrap css file.
If you look at the download of bootstrap css you will see, that there is a file named bootstrap-theme.css . This is a default theme. If you include this file jqGrid will look in appropriate way. With other words you can color your grid using a example of this theme, which will color all other components in your application.