Database ERD design: 2 types user in one table

I have read this (Database design: 3 types of users, separate or one table?)

I decided to put admin and normal user in one table since the attributes are similar:

• fullname,
• address,
• phone,
• email,
• gender
• ...

Then I want to draw ERD, suddenly my mind pop out a question.How to draw?

Customer make appointment and admin approve appointment.now only two tables.Help.