The Style tab controls appearance:
• Highlight color and opacity for the shaded regions
• Outline color and width for the curves
• Circle size
• Switches for the universe box, region labels, and the caption
Drag any curve to move it. At 2 and 3 sets dragging is safe and useful for spacing the picture. At 4 and 5 sets the layout is fixed, and dragging destroys the regions the diagram depends on.
Two export buttons finish the job. Download SVG produces a vector file that stays sharp at any size and can be edited in a vector editor, which is what you want for print, worksheets, or slides. Download PNG produces a raster image for anywhere that will not accept SVG. Set your colors and toggles before exporting, since the file captures the diagram exactly as it appears.