If you want to verify that data is being sent, connect a tool to the UART pins of your microcontroller. This allows you to print debug messages like "Message Sent" or "Message Received" to verify that your code is working.
If your goal is PCB layout rather than active simulation, you can import third-party footprints: : Platforms like PCB Libraries provide free symbols and footprints for the MCP2551. How to Import mcp2551 library proteus