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: 'textarea',
        name: 'name',
        value: 'some text',
        fieldStyle : "color:red;",
        fieldLabel: 'Name',
        allowBlank: false  // requires a non-empty value
    }]
});