I don't see a lot different you could have done. Against a thinking opponent, there's no way I could put him on 777 with the bet on 5th as he'd probably go for a checkraise to attempt to knock out the 3 diamond board, so I'm fine with just a call. Your hand is good enough for a call, but there's no reason to bloat the pot with a raise considering 6th won't be good for you a good bit. Once the fourth diamond gets there and you still just have one pair, fold seems pretty standard with 77 betting into it.
Lee