The ornamental design for a displayscreen or a portion thereof with graphical user interface, as shown and described.
FIG. 1 is a view of a display screen or a portion thereof with graphical user interface;
FIG. 2 is a view thereof, shown in an alternate environment; and,
FIG. 3 is a view thereof, shown in a second alternate environment.
The outer broken line represents a display screen or a portion thereof and forms no part of the claimed design. The broken line showing of the remainder of the graphical user interface forms no part of the claimed design.