One of the lines in "Magic to Do" is "Romance, sex presented Pastorally". The Leading Player is heard repeating that line before "With You".
Pippin is seen shirtless for some of the show.
Basically, "No Time at All" has a verse where Berthe, a 66 year old grandma, sings about her sexual promiscuity and her hope to fall in love at her age ("Give me a man that is handsome and strong...")
A woman is seen with grapes hanging from her breasts. This is done for humor.
A symbolic orgy is seen at the end of "With You", that involves many sexualized dance moves. At one point, a group of men are seein lifting Pippin up, moving women under Pippin, and thrusting pippin up and down on top of them, symbolizing sex with them.
There is a very comical sex scene, where Pippin and Catherine are shown going into bed. The lights go down and spotlights focus on these two dancers who are doing erotic movements. In the background you can see the sheets on the bed moving up and down. The man attempts to catch the woman but fumbles, and Catherine and Pippin sit up apologizing to each other. Pippin hints to the fact that he wants to try having sex again, so they have sex again. The dancers come back out, and the same thing happens, except this time the man catches the woman.
The song "Love Song" is about Pippin and Catherine's love affair, some of the lyrics may be symbolic of sex.