Use the menu item → to save the shown coordinate system as an image file. When the menu item has been chosen, a standard Save As dialog will appear. In this dialog you write a filename, choose a directory and select one of the following image types:
Metafiles are usually preferred because they are small and look nice even when scaled. Though emf files are widely supported under MS Windows, they are not very portable.
This is a format for portable metafiles and should therefore be preferred for files placed on the Internet. However the format is still not supported by all browsers.
Portable Network Graphics (png) is a format that is better compressed than bmp files. This is the most sustainable format for web pages, because it is small and can be understood by all browsers.
Windows Bitmap (bmp) is a standard format supported by almost all Windows programs that can read graphics files.
Joint Photographic Experts Group (jpeg) is a bitmap format with loss. It is supported but not recommended because graphs will usually become blurred.
Portable Document Format (pdf) is actually not an image format. It is a way to store documents as postscript in a portable way. Graph will store the image as Portable Network Graphics inside the pdf file.
The button in the save dialog can be used to change the image size. You may also be able to change other settings depending on the chosen image format.