fieldStyle

http://stackoverflow.com/questions/13771723/change-color-of-xtype-text-in-extjs4-1

HTML

<link rel="stylesheet" href="http://cdn.sencha.io/ext-4.1.0-gpl/resources/css/ext-all.css">

JavaScript

Ext.create('Ext.form.Panel', {
    title: 'Contact Info',
    width: 300,
    bodyPadding: 10,
    renderTo: Ext.getBody(),
    items: [{
            xtype: 'text',
            padding: '64 0 0 0',    
            text: "Logged in as:",
            textAlign:'left',
            fieldStyle : "color:red;",
            style : "color:red;",         
             width: 140,

            }]
});