use Tie::Cycle; # in the CPAN

tie my $cycle, 'Tie::Cycle', [ qw( FFFFFF 000000 FFFF00 ) ];

print $cycle; # FFFFFF
print $cycle; # 000000
print $cycle; # FFFF00
print $cycle; # FFFFFF  back to the beginning    

(tied $cycle)->reset;  # back to the beginning