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; and,
FIG. 2 is a view of a second embodiment thereof.
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.