Fastest Way to put data into the graph

The absolutely fastest way? I don't know. The strategies I am aware of:
Without changing the way the data are arranged in your spreadsheet
1) Copy a range to the clipboard -> paste into chart. You can also paste special to control some of the default options, but that will obviously be slower than the simple paste command.
2) Use select data dialog -> Add series -> select ranges from the add series dialog
3) With chart selected, the chart source data area is highlighted. Grab a corner of the chart source data and drag to include new series.

(3) is probably fastest when it is applicable, but it will only be applicable if your data is arranged in the spreadsheet in a way that you can simply drag across to add series. (1) is probably second fastest, unless the default choices behind the paste operation fail. Then you end up deleting the newly added series and figuring out how to add the data series. I find the select data dialog sometimes the fastest way because it is the most precise and the least prone to errors (because, no matter how fast an operation is, if it is done wrong, it ends up being slower than getting it right).

If you are willing to rearrange the data so that it all of the data that you want in the chart (and only the data you want in the chart) goes across the spreadsheet, instead of having multiple tables going down the spreadsheet, then you can more reliably use (3). Setting it up takes longer, because you need to think through the data layout in the spreadsheet. Once it is set up, though, adding and removing series will be much faster -- as long as you are adding/removing from the left/right edges of the source data range.