ERC20 tokens (like CVC, EOS, GNT, WAX, STORM, SALT) do not have their own public address/private key pair shown in "Display Private Keys". The reason for this is because ERC20 tokens are held on an Ethereum address so they share the public address/private key with Ethereum.
If you would like to see your private key for any ERC20 token, please make sure your ETH wallet is initialized from Menu>Wallets. After that, you will be able to see the same address as your ERC20 token along with the private key for it in Menu>Tools>Display Private Keys>Display Ethereum keys.
Disclaimer: Please make sure you do not share your private keys with anyone, including Jaxx support team, as if someone gains access to them, they will also be able to manage your funds.