Vintage synth forums often have a "Manuals" stickied thread. Users have uploaded the to file hosting services. While these links sometimes expire, the community is active. If you post in the "Vintage Gear" section asking for the VL-1 song sheet, a veteran will likely upload it within a day.
Since I cannot host the file directly on this blog due to copyright technicalities (though Casio has largely abandoned these copyrights), here is the best path: casio vl-tone songbook pdf
If you are using the songbook to learn the instrument today, remember these core VL-Tone functions mentioned in the guides: Note Storage (REC mode) Vintage synth forums often have a "Manuals" stickied thread