Refactor long function by splitting it into multiple smaller functions

[a2ush]

Issue #, if available:

Previously, CreateDiagram() included various operations. Considering future extensibility, these processes should be defined as separate functions.

Description of changes:

• Define them as separate functions (Refactoring)

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.