Let me elaborate more, based on the online sample here: http://es.infragistics.com/products/jquery/sample/grid/row-edit-template

Instead of only changing the appearance of the td and tr tags like this:

    <style type="text/css">
        .tableBackGround
        {
            background-color: #FF7283;
        }
        .labelBackGround
        {
            background-color: #FFE96D;
        }
    </style>
    <script id="rowEditDialogRowTemplate1" type="text/x-jquery-tmpl">    
        <tr class="tableBackGround">                
            <td class="labelBackGround"> ${headerText}
            </td>
            <td data-key='${dataKey}'>
                <input /> 
            </td>
        </tr>
    </script>

Is it possible to change the template completely? Like say if I want to write my own template from scratch yet maintaining all other functionality.

 https://www.igniteui.com/help/api/2019.1/ui.iggridupdating  

 On the above link, click on the “THEMING” tab.  You will find classes like  .ui-dialog-title, ui-dialog-titlebar.

I hope this helps.