I always felt that the disign of CT-S500 is sort of unfinished, people need to use white paint just to make visible all inputs signs. too bad... Taking as an example from white Casio CTS1, I sticked red felt and used grey speaker fabric. I think that how it should be sold to us!
http://img4.imagetitan.com/img.php?image=26_whatsappimage2023-10-06at22.23.09_ab42f901.jpg
http://img4.imagetitan.com/img.php?image=26_whatsappimage2023-10-06at22.22.43_fcf99689.jpg
http://img4.imagetitan.com/img.php?image=26_whatsappimage2023-10-06at22.22.43_7fc0ad50.jpg
http://img4.imagetitan.com/img.php?image=26_whatsappimage2023-10-06at22.22.43_0d456642.jpg
http://img4.imagetitan.com/img.php?image=26_whatsappimage2023-10-06at22.22.42_8880db8c.jpg
http://img4.imagetitan.com/img.php?image=26_whatsappimage2023-10-06at22.22.42_5b0b4e00.jpg
http://img4.imagetitan.com/img.php?image=26_paint987.jpg
Fabric and red felt you can find on Aliexpress for a few dollars... I could not post links here...