Solution:
Within the VC editor it is not possible to give each tab a different color.
You could solve your problem with CSS. I don’t think it’s really that convenient.
#prog-vides-darzs .vc_tta-panel-heading {
background: black;
}
#prog-veselibas-darzs .vc_tta-panel-heading {
background: green;
}
You could repeat this for every item in your accordion.
It could also be possible to do this within the VC editor but this will require some customization to either the core of VC or for you to create a custom VC element.