The ornamental design for a displaypanel or portion thereof with graphical user interface, as shown and described.
FIG. 1 is a front view of a display panel or portion thereof with graphical user interface showing our new design; and,
FIG. 2 is a front view thereof shown with environmental matter.
The dot-dash broken lines illustrate a display panel or portion thereof and form no part of the claimed design. The dash-dash broken lines on the display panel represent portions of the graphical user interface that form no part of the claimed design. The broken lines in FIG. 2 showing a display device illustrate environmental matter that forms no part of the claimed design.