To draw it in OpenGL through Simple Media or any other layer, you'd be best off with the most exact visualization, which is - math.
The most common and, unless you're a prodigal mind capable of drawing perfect natural shapes by hand, the easiest way is via any function capable of drawing circles. You call that function to intersect one, central oval with another six. These six intersecting points are called anchors, and they are relative to your canvas. The latter is, for this example only, the wholesize of your map. Focusing your effort into anchor points is essential because you should be able to use your ViewPort() function to zoom in and out, display minimap or just use scroll as most turn-based strategic games do. Even though it's obvious, the most important anchor point is the central one which adds up to the existing six to use with ViewPort().
This type of grid allows for better item flow across the map and, if used properly, a ton of map items with very few slowdowns.