Is there anywhere I can obtain the data?
No, but it's easy to eyeball that.
See how every hole is right in between switches.
For example the top left one is 2u from left and 1u from top. Convert that in millimiters and you have your first hole.
Set the shape to [-x,-y] so the starting point is the top left corner. Now circle centers would be exactly the number of units of a single switch.
To clarify, again the top left hole is 2u from left and 1u from top, so your first circle center is actually [19.05*2,19.05] or [38.1,19.05] to abbreviate.
Keep adding holes according to this rule and you have your plate. If need any more help, be sure to ask.