I have write a plugin to pick color after textfield.
if you like it, use it free

1st just put it before you use it.

HTML Code:
   	Ext.form.colorPicker = Ext.extend(Ext.form.TextField,{
		fieldLabel:"取色框",
		value:"#000",
		id:"colorPicker",
		listeners:{
			"focus":function(){
				var w = new Ext.Window({
					x:this.getPosition()[0]+120,
					y:this.getPosition()[1],
					title:"test",
					items:[
					{xtype:"colorpalette",id:"innerColorPicker",listeners:{"select":function(palette, selColor){Ext.getDom("colorPicker").value = "#"+selColor;w.hide();}}}
							]
				});
				w.show();
			}
		}
	});
	
	Ext.reg('colorPicker', Ext.form.colorPicker);

Then use it :

var panel=new Ext.form.FormPanel({
frame:true,
layout:'form',
labelAlign:'right',
renderTo:"testForm",
width:400,
items:[{
xtype:"colorPicker",
name:'color'
}]
});


this plugin have been large used in http://www.51widget.com/