To Change Android Button on Click/Press Color :
Define Color Value
To define color value, you have to create colors.xml file in your project values directory and add following.
res/values/colors.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="button_pressed">#ff8a00</color>
<color name="button_focused">#ff8a00</color>
<color name="button_default">#1c76bb</color>
</resources>
Create a XML File in Drawable Directory
Create a button_background.xml file in your drawable folder and add button pressed/clicked, focused and default color. Final code of button_background.xml file looks like this.
res/drawable/button_background.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="@color/button_pressed"/> <!-- pressed -->
<item android:state_focused="true"
android:drawable="@color/button_focused"/> <!-- focused -->
<item android:drawable="@color/button_default"/> <!-- default -->
</selector>
Adding Buttons
res/activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@drawable/button_background"
android:text="Click Me"
android:textColor="#fff" />
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/button1"
android:layout_marginTop="16dp"
android:background="@drawable/button_background"
android:text="Click Me"
android:textColor="#fff" />
</RelativeLayout>
Source here.