nesse exemplo eu usei somente pro botao "sim".E fiz a mesma coisa pra um "nao".
<selector xmlns:android="
http://schemas.android.com/apk/res/android">
<item android:state_checked="true" android:state_window_focused="false"
android:drawable="@drawable/yes_clicked" />
<item android:state_checked="false" android:state_window_focused="false"
android:drawable="@drawable/yes_gray" />
<item android:state_checked="true" android:state_pressed="true"
android:drawable="@drawable/yes_clicked" />
<item android:state_checked="false" android:state_pressed="true"
android:drawable="@drawable/yes_gray" />
<item android:state_checked="true" android:state_focused="true"
android:drawable="@drawable/yes_clicked" />
<item android:state_checked="false" android:state_focused="true"
android:drawable="@drawable/yes_gray" />
<item android:state_checked="false" android:drawable="@drawable/yes_gray" />
<item android:state_checked="true" android:drawable="@drawable/yes_clicked" />
</selector>