Short Answer: As a recent graduate, i would NOT worry about architecture and extensible design, i would rather build strong fundamentals.
It would not be realistic expect this skills from a new grad. However, you are expected to have strong understanding of CS, database concepts and intermediate skills in any OO programming language.
What i would do is, work on my debugging skills and tools to be able to catch-up and understand the code flow in the project that i am assigned to. Thus, being able to read the code, analyse it, learn new technologies/framework as you go - should be my priority to build my initial experience.
Reading about Design Patterns and learning from experience of peer programmers is very useful path to follow.