Try this: journal the surface plot. (Edit->journal).
(Optional) Right-click->settings, make the line weight and font bigger.
Now stretch the surface plot bigger, maybe twice the size of the screen, so you have to scroll the journal to see it all. You'll have to move the sliders and grab the bottom right corner several times. The journal makes it possible to resize the plot bigger than the screen.
Now save that as a PNG file. You can see this image is being squished to make it fit.
actual size looks like this (if your browser is scaled to 100%)
Now you can load the PNG file and resize (smaller) it to fit your needs.
Update: in JMP10 you probably need to use edit->layout rather than edit->journal; the JMP10 journal isn't letting me size the graph bigger.
Craige