Hey
大学(を)卒業した後で 、日本で働くつもりです
大学(を)卒業してから 、日本で働くつもりです
It should be で, に is used when speaking about a place where something exists, so verbs like 住む to live/ いる ある to exist come to mind.
で is used more about a location where something happens. Like working 働く. (basically every case except those where に is used. There are some verbs where both fit though.)
So when you want to say that you drink tea at home, you will use で too.
But if you want to say that the tea canister is located at home you want to use に.
てから implies that there won’t be other actions between graduating and going to Japan to work.
後で is looser, you can say it when you want to work in Japan after few years of getting work experience or something like that.
By the way, you can also say:
大学(の)卒業の後で 、日本で働くつもりです。
Which would mean "after