Looks like you already found one way of saving the graph. Regarding saving the data, the most simple way is to run Serial Monitor, then when you're finished click on the output window, Ctrl + A (select all), Ctrl + C (copy to clipboard), then Ctrl + V into a text editor or spreadsheet program. There are also terminal programs that allow you to save directly to a file. You can use a spreadsheet program to make graphs from the data.