The ornamental design for a displayscreen with an animated graphical user interface, as shown and described.
FIG. 1 is a front view of a first image in a sequence of a display screen with an animated graphical user interface showing my new design;
FIG. 2 is a second image thereof; and,
FIG. 3 is a third image thereof.
The appearance of the animated graphical user interface sequentially transitions between the images shown in FIGS. 1-3. The process or period in which one image transitions to another forms no part of the claimed design. The outermost broken line rectangle illustrates a display screen 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.