The ornamental design for a displayscreen or portion thereof with graphical user interface, as shown and described.
FIG. 1 is a front view of a display screen or portion thereof with graphical user interface showing our new design; and,
FIG. 2 is another front view thereof, showing alternative environment.
The dashed broken lines in FIG. 1 depict a display screen or portion thereof and form no part of the claimed design. The dashed broken lines in FIG. 2 depict a device including a display screen or portion thereof and form no part of the claimed design.