Display Panel or Portion Thereof with Graphical User Interface

This patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. FIG. 1 is an enlarged front view of a display panel or portion thereof with graphical user interface according to a first embodiment of my new design; FIG. 2 is another front view of FIG. 1 with the addition of environmental subject matter; FIG. 3 is an enlarged front view of a second embodiment thereof; and, FIG. 4 is another front view of FIG. 3 with the addition of environmental subject matter. The broken line outline of a mobile device in FIGS. 2 and 4 depicts environmental structure of a display panel or portion thereof and forms no part of the claimed design. The dot-dash broken lines represent boundaries of the claimed design and form no part of the claimed design. All other broken lines in the drawings depict portions of the graphical user interface that form no part of the claimed design.