So, does this help?

#!/usr/bin/perl                                                       
+            
use strict;
use warnings;

use Color::Spectrum qw/generate/;
use List::MoreUtils qw/uniq/;
use Data::Dump qw/pp/;

my %peptides = (
    HISCLTFGR => 16,
    MQLFHLCLI => 8,
    WGMDIDPYK => 4,
    YVNVNMGLK => 3,
    AYRPPNAPI => 2,
    ELMNLATWV => 2,
    EYLVSFGVW => 1,
    FFPSIRDLL => 1,
    FLPSDFFPS => 1,
    IISCSCPTV => 1
    );

my @unique_indices = uniq values %peptides;
my $num_colours = scalar @unique_indices;
my @colours = generate($num_colours, '#FF0000', '#0060BF');
my %values_to_colours;
$values_to_colours{$unique_indices[$_]} = $colours[$_] for 0..$#colour
+s;


pp %values_to_colours;
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