There should be! I'm not entirely sure how Humble fulfills the order... here, let me go through the process myself.
That's what you get when you click on the gift link from Humble in your email. That link in the box is for Defender's Quest 1 -- just give that link to someone.
If you already clicked "claim this page", then in your Humble Bundle library (on humblebundle.com main page, click your name in upper right, then "my library"), scroll down to here:
(I have two copies of it because of testing)
And that will bring up the original box with the giftable link.
Hope this helps!