I just need to update the expiration date on the Credit Card I use for Apple Pay but I don't see that edit option available. How do I update the expiration date?

Mine have always updated automatically. See the following from: Change or remove the payment cards that you use with Apple Pay - Apple Support

If your card expires or you otherwise get a new card:

• The card number and expiration date linked to the Device Account Number should be updated automatically. 
• If your card issuer doesn’t support these updates, you might need to remove the card and add it again.