Number your nodes 1 through 11. Create a vector with 11 elements. Each element in the vector should contain the number of the node that is the parent of the node with that element number (or 0 if that node has no parent.) For example if node 2 was the parent of node 6, element 6 of the vector would be 2.
If you want the nodes to be laid out more closely to how they appear in that picture, with all children of the red 1 being level with the red 2, etc. consider building a digraph and calling plot on the digraph. Specifying the 'layered' layout looks pretty close to the picture you posted, but if you want to get even closer you can explicitly specify the X and Y coordinates for your nodes.
