The ornamental design for a computerdisplayscreen or portion thereof with graphical user interface, as shown and described.
FIG. 1 is a front view of a first embodiment of a computer display screen or portion thereof with graphical user interface showing the new design; and,
FIG. 2 is a front view of a second embodiment thereof.
The broken lines showing a computer display screen or portion thereof with graphical user interface illustrate environment and form no part of the claimed design.