You can make a batch file and put it in your startup folder. Make a new text document and type in
C:\Users\John\Documents\Arduino\libraries\Cayenne\extras\scripts\cayenne-ser.bat -c Com2
Click File>Save As name the file Cayenne.bat and click the Save as type and choose All Files (.) and save to your desktop or somewhere easily accessible.
Hold down the Windows key, and type R, Type: shell:startup, Click OK then copy or move the file you saved to this folder. When you log in next time the cmd window will open automatically.