Order by a ACF Field plus latest post on top

So i’ve created a ACF field “department” so that the different jobs are clustered within departments (See on the page – different colors) but in addition i’d like to have the latest created job withing each “department” (segment) on top of the list. At first all light green jobs with the latest jobs on top, then the light blue jobs with the latest job directly after the green ones.

thanks a lot.

The page I need help with: [log in to see the link]