These links have also been added in the main menu under their respective parent. Both buyers and sellers can see the state of the subscription (either active or cancelled) and only see the creating subscription (not each subsequent subscription). Buyers are able to see the subscription ID as well.
In addition, when a subscription is cancelled you'll get an email notifying you of the cancellation and an alert generated stating the same if you are the seller.
Unfortunately, the Paypal API doesn't allow cancellation of s- type subscriptions. I actually added a cancel link for both buyers and sellers but the API always returns "invalid profile id" which I later learned is because of these s- type which we receive, instead of i- type. For now, all subscriptions will need to be cancelled by the buyer.