[Lizard]

[speaking as a fellow Graffle user, not an official Omni Guru of Graffling]
1) draw a box
2) in the geometry inspector, make its width 2 1/3 inches (or whatever one third of your page is)
3) make it into a table (in toolbar or in the 'Arrange' menu)
4) drag the middle right handle of the box to the right until you have 3 boxes
5) fill each box with text
6) turn off shadows and even borders on the boxes if you want to