While the exam does not require you to use any particular tool (or any tool for that matter) to draw your UMLs, it is assumed that you will be using a tool to create your UML artifacts. Also, the UML tool that you will use for architecture on real life projects is not just for pretty picture creation. It has a lot of added benefits such as ensuring compliance with UML standards, pointing out obvious design flaws, generating code skeletons from UML artifacts, reverse engineering existing codebase into UML models for maintenance etc.
Creating a UML model by hand is not recommended except for the simplest of projects. I don't think any commercial enterprise project would fall in this category. Architect a solution for the
SCEA assignment in a way similar to what you would do in real life, which is to use a good tool for creating your UML models.
Just my opinion though.....
SCEA 5, SCJD,SCWCD,SCJP,PMP,IBM-SOA Solution designer,IBM-XML