Split up your team evenly among the bases (home, 1st, 2nd, 3rd). Start with the first person in each line at the bag (the others are behind paying attention and backing up the play). Start with the ball at home plate and throw to 3rd, 2nd, 1st, then back home. After the player makes the throw, they should rotate to the back of the line so the next payer can move up.
Focus on: good footwork, good catching/receiving technique (i.e. two hands, stepping to the ball with the glove foot), and good throwing technique
Throw the counter-clockwise: instead of throwing to 3rd base, then 2nd, then 1st, and back home, go the other direction. This is a different pivot, requiring different footwork.
Follow your throw: Have players follow their ball to give players more of a workout during the drill. So when the player at home starts the drill off by throwing to 3rd, they will then follow their throw and run to the back of the line at 3rd base.
More balls: add in another ball or two to speed up the drill and make it more challenging
4 One-Hops: instead of a regular throw, have the players one-hop the ball to each other. It's easier to have them make it a LONG hop instead of a short hop. Have them focus on giving a good hop to their teammate while the receiver is focusing on good fielding technique and footwork.
2 One-Hops: you can also do the one-hop drill, but have the person fielding the one-hop make a regular throw to the next base so that they are fielding the ball and making a throw. So you'd have the person at home one-hop the ball to 3rd, the person at 3rd field the ball and make a regular throw to 2nd, then have that person throw a one-hop to the player at 1st and that player fields the one-hop and makes a regular throw home. I would highly suggest having player follow their ball in this one so everyone gets a chance to field the one-hops and make a throw or simply alternate what you do first (i.e. start with a regular throw between home and 3rd, then go with the short hop between 3rd and 2nd).
Obviously you can use these variations in combination with each other or even all at the same time (go counter-clockwise, have the players follow their throw, use an additional ball, and do one-hops). WOW!