Display Device with a Graphical User Interface

The sole FIGURE is a front view of a display device with a graphical user interface showing the claimed design. The outermost broken line illustrates the display device and forms no part of the claimed design. The remaining broken lines illustrate portions of the graphical user interface and form no part of the claimed design. Each of the following are broken lines and form no part of the claimed design: the dot grid pattern included in the cat depicted in the second column, the dot grid pattern included in the cat collar depicted in the third column, and the dot grid pattern included in the three cans of cat food depicted in the fifth column.