Can't help you with a grepping module, just wanted you to know that many modern terminals support full RGB colors:

my $newfgcolor = "\e[38;2;" . join(';', $r, $g, $b) . "m";
...
my $newbgcolor = "\e[48;2;" . join(';', $r, $g, $b) . "m";
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See also:

• Re: Imagecat - show color images in a terminal
• "Terminal Velocity", a better Linux terminal graphics demo
• "Terminal colors" Github repo
• ANSI colors discussion on stackoverflow
• "ANSI Escape sequences" (github)

As for doing multiple matches in a program, you could just build a hash with regex+color, then iterate over over it, roughly something like this:

my %matches = (
    qr/hello/ => 'FFFF00',
    qr/world/ => '00FF00',
...
);

...
foreach my $rex (keys %matches) {
    if($input =~ $rex) {
        my ($r, $g, $b) = hex2rgb($matches{$key});
        ...
        last;
    }
}
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