How it works...

Inside our diagram, we define two main objects, nodes and edges. We define two nodes, and we define multiple edges that specify how everything will be connected. For each element, we can define the label that will be shown, and the color. The label and color arguments are used to specify the text and color that will be displayed for each node.

We use the fixedsize and the width parameters to force the elements in the corresponding node to have the same size. Had we not, then the circles for those nodes would be of different sizes.

The grViz() function is used to build the Graphviz diagram, as shown in the following screenshot: