2021-04-16: Here is one in JavaScript.
THANK YOU SILESKY
Toggle Grayscale
tell application "System Preferences"
activate
set the current pane to pane id "com.apple.preference.universalaccess"
delay 1 # needs time to open universal access
tell application "System Events" to tell process "System Preferences" to tell window "Accessibility"
tell scroll area 2 to tell table 1 to tell row 6 #open display preferences
select
end tell
click checkbox "Use grayscale"
end tell
end tell
tell application "System Preferences" to quit
# Sierra: System Preferences -> Accessibility -> Display -> Use grayscale
Invert Colors
tell application "System Preferences"
activate
set the current pane to pane id "com.apple.preference.universalaccess"
delay 1 # needs time to open universal access
tell application "System Events" to tell process "System Preferences" to tell window "Accessibility"
tell scroll area 2 to tell table 1 to tell row 6 #open display preferences
select
end tell
click checkbox "Invert colors"
end tell
end tell
tell application "System Preferences" to quit
# Sierra: System Preferences -> Accessibility -> Display -> Invert colors
Aliases
Run them from the command line. Maybe make your screen black and white at night or invert colors for screencasts or working in sunligh.
alias togglegrayscale=’osascript /Users/gcr/util/sspadtogglegrayscale.scpt’
alias invertcolors=’osascript /Users/gcr/util/sspadtogglecolors.scpt’