Modeling Subclass (or Subtype) Constraints in an Entity-Relationship Diagram
I think you can make an Orders entity that is a relationship between Products and Customers. The Orders would have subclasses FoodOrders and ShoeOrders, which respectively would be the relationships between the subclasses of Food - GroceryStores and Shoes - ShoeStores.

                                            ┌───────────┐
                                            │ Employees │
                                            └─────┬─────┘
                                                  │
                                                  │
      ┌──────────┐               ┌────────┐       │       ┌───────────┐
      │ Products ├─── contain ───┤ Orders ├─── deliver ───┤ Customers │
      └────┬─────┘               └────┬───┘               └─────┬─────┘
           │                          │                         │
           │                          │                         │
          isA                        isA                       isA
          │ │                        │ │                       │ │
     ┌────┘ └────┐             ┌─────┘ └─────┐            ┌────┘ └────┐
     │           │             │             │            │           │
 ┌───┴──┐    ┌───┴───┐         │             │    ┌───────┴───────┐   │
 │ Food │    │ Shoes │         │             │    │ GroceryStores │   │
 └───┬──┘    └───┬───┘         │             │    └───────┬───────┘   │
     │           │       ┌─────┴──────┐      │            │     ┌─────┴──────┐
     └───────────│───────┤ FoodOrders ├──────│────────────┘     │ ShoeStores │
                 │       └────────────┘      │                  └─────┬──────┘
                 │                     ┌─────┴──────┐                 │
                 └─────────────────────┤ ShoeOrders ├─────────────────┘
                                       └────────────┘