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 a front view of a display panel or portion thereof with graphical user interface; and, FIG. 2 is another front view of FIG. 1 with the addition of environmental structure. The broken line outline in FIG. 1 indicates portions of the display panel or portion thereof that form no part of the claimed design. The broken line outline of a mobile device in FIG. 2 depicts environmental structure of a display panel or portion thereof and forms no part of the claimed design. The dot-dash broken lines forming rectangles in the figures represent boundaries of the claimed design and form no part of the claimed design. All other broken lines in the drawings (including the gray dash-dash broken lines) depict portions of a graphical user interface that form no part of the claimed design.