Visual Studio color settings, does not have yellow Enum? its colored as a Class?

You can go to "Preferences | Editor | Colors & Fonts | Language Defaults", then locate "Classes | Enum" in that window and set the appropriate color(s).

In the future, consider mentioning which color scheme you are using (which you selected when you first ran Rider). This also doesn't seem like a "Feature Request" and should probably be posted as a trivial bug at: https://youtrack.jetbrains.com/issues

Hope this helps!