I'm assuming that you are just making one of these. If you need to do this in production, find someone with a suitable machine.
I would use a variant of JFettig's suggestion. First, I would layout one instance of the pattern on an aluminum template and drill it with pilot holes. Then I would layout the circle on my material. I would manually layout the four quadrants (since you have sixteen repeats). -- Use a compass and layout dye.
Then, I would layout the rest of the holes, recognizing that I can do eight of them by indexing off the four quadrant lines. The remaining four would be done as JFettig suggested, but I would just use the template and a center punch.
I would then drill all of the holes using a drill press (or use your mill as a drill press). Drill the holes undersized and ream them to fit the bushings you've selected.
There should be no problem getting the holes within .010 using this approach if you are careful.
Ken
Kenneth Lerman
55 Main Street
Newtown, CT 06470