This is actually the default -- public graphs but private data. Want to try it out in a different browser where you're not logged in and check if it's giving you the level of privacy you're looking for? We definitely want to encourage people to share/hotlink their graphs. In fact, I'm glad you asked this even if we're already doing what you wanted, since it means we need to make it more clear somehow that it's safe to link to your graph even if you're putting potentially embarrassing things in the datapoint comments. (Unless you *want* to share your data and comments in which case you can check "public data" in the goal settings.)

(or, in this case, data point comments is really my problem)