The ornamental design for a displayscreen or portion thereof with graphical user interface, as shown and described.
The FIGURE is a front view of a display screen or portion thereof with a graphical user interface. The broken line showing of text, lines, boxes and map elements illustrate portions of the graphical user interface and form no part of the claimed design. The outermost broken line rectangle illustrates a display screen or portion thereof and forms no part of the claim design. Variations in the broken line types used are based on the length of the text, line, box or map element being shown and therefore the broken line lengths used include short broken lines, long broken lines and dotted broken lines as needed without having any significance based on the type of broken line used other than being broken lines that illustrate portions of the graphical user interface that form no part of the claimed design.