This is a Visual Studio Professional or better feature. Express doesn't have the Code Visualization and class Designer features (nor any of the other UML features).
As far as I can tell there is no official feature comparison for Visual Studio that includes the Express editions. But there is a blog post that describes the 2012 features and they have remained almost identical with the upgrade to 2013.
The 2013 feature comparison for the other editions can be found here.
UPDATE
Now that the Visual Studio Community Edition is available, you may be able to use that instead of Express. It depends on whether you fall in the license category for the Community Edition:
Q: Who can use Visual Studio Community?
A: Here’s how individual developers can use Visual Studio Community:
- Any individual developer can use Visual Studio Community to create their own free or paid apps.
Here’s how Visual Studio Community can be used in organizations:
- An unlimited number of users within an organization can use Visual Studio Community for the following scenarios: in a classroom learning environment, for academic research, or for contributing to open source projects.
- For all other usage scenarios: In non-enterprise organizations, up to 5 users can use Visual Studio Community. In enterprise organizations (meaning those with >250 PCs or > $1 Million US Dollars in annual revenue), no use is permitted beyond the open source, academic research, and classroom learning environment scenarios described above.