GoJS in 12 Minutes Video Code

Link to video here.

const $ = go.GraphObject.make;

const myDiagram = new go.Diagram("myDiagramDiv");
const nodeDataArray = [
    { key: "Alpha", color: "lime" },
    { key: "Beta", color: "cyan" },
    { key: "Zeta", isGroup: true },
    { key: "Delta", color: "pink", group: "Zeta" },
    { key: "Gamma", color: "maroon", group: "Zeta" }
  ];
const linkDataArray = [
    { to: "Beta", from: "Alpha", color: "red" },
    { to: "Zeta", from: "Alpha" }
  ];
myDiagram.model = new go.GraphLinksModel(nodeDataArray, linkDataArray);

myDiagram.nodeTemplate =
  $(go.Node, "Auto",
    $(go.Shape, "RoundedRectangle", { fill: "white", },
        new go.Binding("fill", "color")
    ),
    $(go.TextBlock, "text", { margin: 10 },
        new go.Binding("text", "key")
    )
  );

myDiagram.linkTemplate =
  $(go.Link,
    $(go.Shape, { strokeWidth: 3 },
        new go.Binding("stroke", "color")),
    $(go.Shape,
    { toArrow: "Standard", stroke: null },
        new go.Binding("fill", "color"))
  );