Terretektorh / Nomos Gamma (no date; late 60s) by Iannis Xenakis.
Xenakis and Victor Vasarely are paired again on this album cover from the late 1960s. Given how often record companies have used abstract artwork on the sleeves of classical recordings, especially those by 20th-century composers, you’d expect there to be more examples. There may well be but Discogs (always the easiest place to search) only turns up the following examples.
Chamber Concerto For 11 Instruments / Symphonic Variations (no date) by
Neils Viggo Bentzon / The Royal Danish Orchestra conducted by Jerzy Semkow.
Kontakte For Electronic Sounds, Piano And Percussion / Refrain For Three Instrumentalists (1968) by Aloys Kontarsky, Christoph Caskel, Karlheinz Stockhausen.
David Bowie (1969) by David Bowie.
I confess that until I began searching for Vasarely covers I hadn’t known that this was an early example. That’s partly down to David Bowie’s second album (the first in his official canon) having been reissued for years in a different cover with Bowie’s face filling the sleeve. The album reissues in 1999 restored the original design, one of the artist’s Folklore Planetaire series. The credit is to “Vaserelli”.