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 our new design. In the drawing, the broken lines showing the display screen are for the purpose of illustrating environment and form no part of the claimed design. The remaining dotted, broken lines illustrating all text, icons, and greyscale elements of the graphical user interface form no part of the claimed design.