Set com.google.android.material.chip.Chip selected color

Just set an attribute app:chipBackgroundColor and pass a color state list to it:

<android.support.design.chip.Chip
    android:id="@+id/test"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:checkable="true"
    android:clickable="true"
    android:focusable="true"
    app:chipBackgroundColor="@color/bg_chip_state_list"
    app:chipText="Test" />

bg_chip_state_list looks like this:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="@color/colorSecondaryLight" android:state_checked="true" />
    <item android:color="@color/colorPrimaryDark" />
</selector>

However I also had to set android:clickable to true to make this work

Using a ColorStateList is a proper way. The only thing I want to add is using custom defined style much more clear to read especially if you want to customise a bunch of properties.

Among other things, one common style applied to all views allows you to make changes in one place that apply immediately to all views

styles.xml

<style name="CustomChipChoice" parent="@style/Widget.MaterialComponents.Chip.Choice">
        <item name="chipBackgroundColor">@color/background_color_chip_state_list</item>
        <item name="android:textColor">@color/text_color_chip_state_list</item>
</style>

text_color_chip_state_list.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_checked="true"
        android:color="@color/color_checked" />
    <item android:state_checked="false"
        android:color="@color/color_unchecked" />
</selector>

background_color_chip_state_list.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="@color/color1" android:state_checked="true" />
    <item android:color="@color/color2" />
</selector>

After that all you need is apply your custom style for all the Chip views like this.

<android.support.design.chip.Chip
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    style="@style/CustomChipChoice"
    android:checkable="true"
    android:clickable="true"
    android:focusable="true"
    android:text="Chip text" />