The cover for The Case of Charles Dexter Ward in Portuguese translation, published from Lisbon in (apparently) 1941.
The Lovecraft bibliography has this as “1958?”, but the eBay seller who provided this scan and who had the book to hand stated 1941. Colour covers during wartime seems a little unlikely, though. But possibly they were expected on paperbacks in Brazil and wouldn’t sell well without colour?
An article on Lovecraft in Portuguese suggests “1956”, and — although that claim is unreferenced — the date does seem to match the illustration style and the use of colour.