Via reboot81:
Open Script Editor and paste each block into a new script for you to use.
Invert Colors
var systemEvents = Application("System Events");
var systemPreferences = Application("System Preferences");
systemPreferences.activate();
systemPreferences.panes.byId(
"com.apple.preference.universalaccess"
).anchors.byName("Seeing_Display").reveal();
chkInvert = systemEvents.applicationProcesses.byName(
"System Preferences"
).windows.byName("Accessibility").checkboxes.
byName("Invert colors");
systemEvents.click(chkInvert);
systemPreferences.quit();
Toggle Grayscale
var systemEvents = Application("System Events");
var systemPreferences = Application("System Preferences");
systemPreferences.activate();
systemPreferences.panes.byId(
"com.apple.preference.universalaccess"
).anchors.byName("Seeing_Display").reveal();
chkInvert = systemEvents.applicationProcesses.byName(
"System Preferences"
).windows.byName("Accessibility").checkboxes.
byName("Use grayscale");
systemEvents.click(chkInvert);
systemPreferences.quit();