What is the Maven versioning strategy for Continuous Delivery or Deployment?
we now want to release faster


And from your comment:


  Basically, since the artifacts depend on each other, we need to release them in the correct sequence. And since there's a lot of them, it takes some time.


I think you're having an X/Y problem. Yes, versioning plays a role, but it seems like you would benefit from solving the source of your problem first, which is that you have to release something in the correct sequence; presumably you also have to release everything at the same time, with a large downtime of the whole system.

Try to reach a state where you can release new versions of each artifact in arbitrary order. This basically means:


Employing some form of Dependency Injection (which is a big word, but can be something pretty simple, depending on how your software works). 
You need to be able to have multiple versions of each artifact on the server at the same time, and to switch between them without much effort. That "switch" should be be on the side of the "user" of an artifact, not on the artifact itself, if you can do so at all. 
Wherever you can, it also is great to be able to run multiple instances simultaneously (obviously this is restricted for data management stuff, databases and such).


I'm not telling you how to do that or that it is easy - I don't know your architecture or technical constraints. But this should give you a general roadmap. 

When you have that capability in place (at least conceptionally), then you will be able to release smaller parts more often, and a little more independently. And - to answer your actual question - sticking with SemVer is then not the worst you can do.