This is a MagicaVoxel palette based on a series of slices through the Hue-Lightness-Saturation (HLS, aka HSL) colour model. I find this more organised than the default palette, while also providing the light and dark colours which are missing from some other hue-based palettes. The generated disks do not include pure greys so those are provided at the bottom.
Download hls.png and place in in your MagicaVoxel 'palette' folder. Then click 'Open' from the 'Palette' panel on the left-hand side and select the downloaded file.
The code and resulting palette are released to the public domain under the Creative Commons Zero license.