javascript – Google Organization Chart from SharePoint list items

I created a Google Organization Chart on SharePoint using the answer from the following question on Stack Overflow.
https://stackoverflow.com/questions/33796219/organization-chart-from-sharepoint-list-items

Items for the Organization Chart are retrieved from a Custom SharePoint List using REST and Javascript.

My question is, how should I modify the code below to show job titles below each name in the Organization Chart?
(Job titles are stored in the custom SharePoint list)

<script src="https://www.gstatic.com/charts/loader.js" type="text/javascript"></script>
<script src="https://code.jquery.com/jquery-3.0.0.min.js" type="text/javascript"></script>
<script language="javascript">
google.load("visualization", "1", { packages: ("orgchart") });
google.setOnLoadCallback(displayChart);


 function displayChart()
 {
     loadListItems('Organization_Chart')
     .done(function(data){
          var items = data.d.results;     
          drawChart(items); 
     })
     .fail(function(error){
          console.log(error);
     });
 }

function drawChart(items) {

    var data = new google.visualization.DataTable();
    data.addColumn('string', 'Name');
    data.addColumn('string', 'Manager');
    data.addColumn('string', 'ToolTip');

    for (var i = 0; i < items.length; i++) {
         data.addRow((items(i)('Title'),items(i)('Manager')('Title'),''));
     }    
     var chart = new google.visualization.OrgChart(document.getElementById('chart_div'));
     chart.draw(data, { allowHtml: true });
}


function loadListItems(listTitle){
     return $.ajax({            
             url: _spPageContextInfo.webAbsoluteUrl + "/_api/Web/Lists/GetByTitle('" + listTitle + "')/items?$select=*,Title,Manager/Title&$expand=Manager",
             type: "GET",
             headers: {
                    "accept": "application/json;odata=verbose",
             },
             error: function (error) {
            alert(JSON.stringify(error));
        }
     });             
}
</script>
<div id="chart_div"></div>

Custom SharePoint List stores each employee’s name, manager, and job title.

SharePoint List has the following schema:

Field Name  Type 
Title       Text 
Manager     Lookup
Job_Title   Text