You've probably already received a lot of good suggestions on what skills you should have. There are computer languages, operating systems, design automation packages, etc., etc.. But something I've learned in teaching students engineering courses is that a very good preparation is of mindset. I'll explain.
In college much of what you do is as an individual contributor. In technology, the trend has always been to do more with less, bigger projects, more complicated problems, more numerous and complicated interfaces, etc.. Because of that, teams get larger. You will have, on any job, far more interfaces to other people and groups than you had in college or any other previous education. The impact of this is that you will need to change your focus to include communication skills to a greater degree.
I have often had new employees complain that they don't make as much progress as they think they should. "I was a great student! I know all the material! I'm doing a good job!" The problem is that they're still in "individual contributor mode".
1) You won't be on any particular job forever. You'll move on. You'll be replaced. You'll find other projects, other companies, other teams. You need to be good at sharing knowledge. Documentation. Communication. Presentations.
2) You need to "sell" your ideas. Everyone in your organization has about as much to do as they can possibly do. So everyone has to prioritize their focus. In college, you got an assignment and that was exactly what you did. In a business, you have essentially an additional "teacher" in every other employee who will be providing you potential assignments or "deliverables" that you can choose to do or not. Sure, there will be obvious required things, but there are also a lot of things you can choose to do. And the same thing goes for everyone else. So if you have a great idea, or do something you think is really important, or have solved a particular problem, you need to not only share this, but you need to convince other people that it's important enough for them to spend their own valuable time to learn about. And that's how you become essential to the team.
3) Number (2) above requires that you be able to present ideas one-on-one and to an audience. Your value is no longer limited to what you yourself do, but to how many interfaces you can leverage to multiply your effectiveness. Humility is a good thing, but being humble and shy all the time is, as they saying goes, "hiding your light under a bushel". If you only get your assignment done and no one else but your boss knows about it, you're depriving the company of a large potential resource.
Your work does NOT "speak for itself". You have to do your part of that, too.