You can model the tables in an Entity Relationship diagram using labels with HTML markup inside. This allows you to easily show attributes with their field details.
The following HTML markup in a label creates a table that shows attribute names of an entity together with their field details:
You can use this markup in the second label of an "Entity with Attributes" symbol from the Entity Relationship palette section, for example:
Entity with some attributes and their field details
...but also in labels of any other node representation.