You can add custom colors to the TINYMCE editor, and this is especially handy if you want clients to stick to their color palette. Please be aware that this function gets rid of all colors and just adds in your selection.

Add custom colors to TinyMCE.php

// TINYMCE Options
function my_mce4_options( $init ) {
  $custom_colours = '
    "db1e34", "Color Name", "222c64", "Color Name Two"
  ';
  $init['textcolor_map'] = '['.$custom_colours.']';
  $init['textcolor_rows'] = 6;
  return $init;
}
add_filter('tiny_mce_before_init', 'my_mce4_options');