Generate a Narrative Report to obtain an SVG drawing of the GenoMap. Download and install the open source Inkscape package. Open the SVG version of the GenoMap from your report's 'genomaps' folder using Inkscape. Click File/Document Properties.. and choose your desired canvas size & orientation (as big as you like!). Now drag the drawing onto the canvas area using Edit/Select All (or Ctrl/A) and use the mouse to drag into the top corner of the canvas. Then use View/Page (or press key 5) to see the whole canvas. Select all again, hold down Ctrl key and drag bottom left arrow to scale the drawing uniformly to fit your canvas. Select & delete the unwanted pink circle and overlaid green arrows from the centre of the drawing. You may want to Select All again and drag to centre the drawing on the page.
You can also now edit the drawing, add images etc. as required.
Finally use File/Export Bitmap... to create a scaled PNG image.