Or as an array of arrays:

use strict;
use warnings;

$| = 0;

my $str="A: Gold, Black, Purple, Blue, Red     B: Black, Neon Pink, Ne
+on Yellow, Neon Green, Neon Purple, Red, White, Neon Orange, Navy";

my @records;
my @strings = $str =~ m/(\w+:(?:(?!\b\w+:).)*)/g;

push @records, map {[m/(\w+:)/, m/(?<=:|,)\s([^,]*,?)/g]} @strings;

print "@$_\n" for @records;
[download]

Prints:

A: Gold, Black, Purple, Blue, Red     
B: Black, Neon Pink, Neon Yellow, Neon Green, Neon Purple, Red, White,
+ Neon Orange, Navy
[download]