The ornamental design for a displayscreen or portion thereof with graphical user interface, as shown and described.
The sole FIGURE is a front view of a display screen or portion thereof with graphical user interface showing the new design.
The outermost rectangle in broken lines in the FIGURE depicts the display screen or portion thereof and forms no part of the claimed design. The remaining broken lines depict portions of the graphical user interface and form no part of the claimed design.