TextView TV = (TextView)findViewById(R.id.mytextview01);
 Spannable word = new SpannableString("Your message");

 word.setSpan(new ForegroundColorSpan(Color.BLUE), 0, word.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

 TV.setText(word);
 Spannable wordTwo = new SpannableString("Your new message");

 wordTwo.setSpan(new ForegroundColorSpan(Color.RED), 0, wordTwo.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
 TV.append(wordTwo);

<string name="signal_msg3">
        <![CDATA[
        Добавьте номера Ваших близких в <font color='#cc0000'>Экстренные контакты</font>
        ]]>
</string>