Change the text color of one of the buttons in DatePickerDialog?

You can make a different style for CANCEL button like below.

<style name="DatePickerTheme" parent="Theme.MaterialComponents.Light.Dialog.Alert">
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="android:buttonBarNegativeButtonStyle">@style/DatePickerTheme.ButtonBarNegativeButtonStyle</item>
</style>

<style name="DatePickerTheme.ButtonBarNegativeButtonStyle" parent="Widget.MaterialComponents.Button.TextButton.Dialog">
    <item name="android:textColor">@android:color/holo_red_light</item>
</style>

You can get the Button from Dialog and modify it attributes using getButton(). See the example below. Get the button after calling .show()other wise it will give a null.

 final Calendar c = Calendar.getInstance();
            int mYear = c.get(Calendar.YEAR);
            int  mMonth = c.get(Calendar.MONTH);
            int mDay = c.get(Calendar.DAY_OF_MONTH);
            DatePickerDialog datePickerDialog = new DatePickerDialog(ConstarintsActivity.this,
                    (view, year, monthOfYear, dayOfMonth) -> {


                    }, mYear, mMonth, mDay);
            datePickerDialog.show();
            datePickerDialog.getButton(DatePickerDialog.BUTTON_NEGATIVE).setTextColor(Color.GREEN);