The following script arranges the icons of the chosen folder’s window, and of all its subfolders’s windows.
set rootFolder to choose folder
tell application "Finder"
open rootFolder
set theFolders to {folder rootFolder} & (every folder of entire contents of rootFolder)
repeat with aFolder in theFolders
set containerWindow to container window of aFolder
tell containerWindow to tell its icon view options to set arrangement to snap to grid
end repeat
close container window of rootFolder -- close and open window again, to see changes
open rootFolder
end tell