#!c:/perl/bib/perl -w
$|++;

use strict;

my %map = (
   S => 0, M => 1, L => 2, Xl => 3
);

my @sorted = 
   map { $_->[0] }
   sort {
      ( $map{$a->[1]} <=> $map{$b->[1]} ) ||
      ( $a->[2] cmp $b->[2] )
   }
   map { chomp; /^\w+:\s+(\w+),\s+\w+:\s+(\w+)$/; [$_, $1, $2] } <DATA>;

print join("\n", @sorted);

__DATA__
size: L, color: White
size: M, color: Orange
size: M, color: White
size: M, color: White
size: S, color: Orange
size: S, color: White
size: Xl, color: Orange
size: Xl, color: White
size: Xl, color: White