Display Panel or Portion Thereof with Graphical User Interface

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 long dash-short dash broken lines represent boundaries of the claimed design and form no part of the claimed design. The evenly spaced broken lines forming a rectangle in FIG. 1 depict a display panel or portion thereof and form no part of the claimed design. The evenly spaced broken lines in FIG. 2 showing a display device illustrate environmental matter that forms no part of the claimed design. The solid black surface shading represents a contrast in appearance.