Hi there,
As you can see the whole UE4 code base is pretty large. I am sure there are some tools with which I can visualize a large project such as UE4. I mean you do not possibly look upon thousands of file for a simple problem solving or understanding a simple matter, do you?
Guys kindly suggest me some tools.
Visual Studio
Can you be a little bit more specific? I mean the specific tools of visual studio. For the record, I am using visual studio too. The class diagram of VS is not really that helpful. It shows individual classes in the diagram but it does not show how they are related. Or may be I am missing some options. I would be delighted if you shed some light on this.
It just takes time. I’ve seen people make mind maps, or run doxegen, but it really just comes down to studying it, your learning style and putting in the time. There’s no shortcut to understanding a large code base you just have to work with it.
You mean a compiler(gcc-g++/clang-llvm/ms) can find an entry point, fetch every class in a project, fetch the commands for builds(makefile stuff) etc but there is absolutely no tool out there which can present all the classes and the translation units in a nice node based network to visualize??!! 
I am quite surprised to hear such a misery or you can say I tend to disbelieve?! 