draw_btn.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:state_pressed="true"
        android:drawable="@drawable/draw_btn_pressed"/>

    <item
        android:state_pressed="false"
        android:drawable="@drawable/draw_btn_idle"/>

</selector>

draw_btn_idle.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape>
            <gradient
                android:startColor="@color/colorStart"
                android:endColor="@color/colorEnd"/>
            <corners
                android:radius="8dp"/>
        </shape>
    </item>

</selector>

draw_btn_pressed.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape>
            <gradient
                android:startColor="@color/colorStartPressed"
                android:endColor="@color/colorEndPressed"/>
            <corners
                android:radius="8dp"/>
        </shape>
    </item>

</selector>