I like to make my architecture diagrams in PlantUML and have them in source control.
Inspired by plantuml-icon-font-sprites, I copied the icons from Sitecore documentation and made sprites, so they can easily be used in diagrams.
!define SC_SPRITESPATH https://raw.githubusercontent.com/jballe/plantuml-sitecore-icons/master/sprites
!includeurl SC_SPRITESPATH/common.puml
!includeurl SC_SPRITESPATH/scWeb.puml
SCWEB(cm, "Content\nManagement")
Will give you
You can embed diagrams from public sources by using plantuml as above. For private repos I often generate an image url with the source embedded, like when using PlantText.com
I can also recommend the VS Code extension for PlantUML