SAMPLE CODE:

Tutorial_Dialog_ColorPickerActivity

reference:

http://code.google.com/p/android-color-picker/

http://www.yougli.net/android/a-photoshop-like-color-picker-for-your-android-application/

http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/ColorPickerDialog.html