This is a very direct and clean “ follow the leader” type effect.
Performer displays 2 packets of Jumbo cards one with all red cards, and one with all black ones. Two spectators are invited to assist, and the packet with red cards tied with a red ribbon on the palm of one spectator, and the packet with black cards tied with a black ribbon on the palm of another spectator.
An Ace of each color is selected, as a leader card, and placed between the fingers of the spectators as a “marker”.
The two aces are now switched across, so the red ace is over the packet of black cards, and the black ace over the packet of red cards. When the packets are removed from the ribbon and fanned, they are found to have switched places, with all the black cards following the black Ace, and the red cards the red Ace.