I don't think you can exchange colour presets from different machines?
What you can do is save a colour by grabbing it from the bottom right square to the right grid with all the empty squares. You can rearrange all your saved colours by dragging them from one spot in the grid to another, the other saved colours will move out of the way.
To get colours from one machine to the other only thing I can think of is write down the HEX code and save them again on the other machine.
That's the OSX color picker. You can do this in any app that you can pop up the color picker.
1. Create a new pallet via the gear looking icon
2. You'll now see an empty pallet called "Unnamed" (you can rename it if you like with the same gear looking icon)
3. Drag your custom swatches up from the bottom and into the area where the colors are normally located
4. When you've done that with all the colors you want to share, copy the pallet file to the same location on the other machine.
It's located here and will be called Unnamed or whatever you renamed it to: