The ornamental design for a displayscreen with a color icon, as shown and described.
The file of this patent contains at least one drawing/photograph executed in color. Copies of this patent with color drawing(s)/photograph(s) will be provided by the Office upon request and payment of the necessary fee.
The FIGURE is a front view of a display screen with a color icon showing my new design.
The broken line showing of the display screen forms no part of the claimed design.