A context diagram is a common view of your system in its environment or domain but is not a SysML product. You can create a context view using SysML. My recommended way is to create your system model by defining your use cases (see use case video) and the system domain using a bdd diagram with the top block called your system domain. In the domain is your system of interest (SOI) and other related blocks outside the system but influential to your system. I also call this level 0. This includes users, the environmental elements (rain, snow), constraints like laws or regulatory bodies. Also you might include hazards like bad weather or bad actors who might do your system harm, also know as off-nominal use cases. From the BDD you can now create the IBD, internal block diagram and link the blocks and annotate their relationships. These relationships can be requirements for your system and important stakeholders who need some function or output of your system. This is standard systems engineering stuff but can easily be included in the beginning development of your systems model. Good luck, Wes