Here you can download the DAX and PowerQuery User-Defined Language (UDL) XML files for easy import into Notepad++ and further customization.
Follow the instructions in the video to
- enable syntax highlighting
- enable auto-completion
- modify the syntax colors to your liking
for DAX and PowerQuery (M).
Two zip archive with the relevant XML files for Notepad++ to enable syntax highlighting and autocomplete for DAX and PowerQuery.