Open the extension files from the development hub http://localhost:4848/dev-hub/ or using any code editor like notepad++ and modify the code to fit your requirement.
It would be very helpfull if you debug the visualization to understand its flow of code and plan your modification accordingly.
To enter the debugging mode use Ctrl+Shift+Right click and select Show Dev Tools.
Let me know if you need any help understanding extension
Let us know how you do.
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