The Steampunk genre takes place in Great Britain during the Victorian era, but that doesn't mean your character is limited to being a Briton. Some cosplayers prefer to Steampunk characters from other parts of the world during the late 19th century. We see this in "Civil War Steampunk" costumes, as well as "Weird West" costumes, which combine Steampunk elements with historical American dress.
If you're looking to create a multicultural character, choose a country and then do some research into what life was like during the late 1800s. What was the traditional style of dress? How would advanced steam technology have impacted daily life? Let this research inspire the creation of your character.
For more information on creating a non-American or Briton character, check out the blog Beyond Victoriana. It focuses on multicultural Steampunk "on non-Western cultures, underrepresented minorities in Western histories (Asian / Pacific Islander, Middle Eastern, First Nation, Hispanic, black / African & other marginalized identities), and the cultural intersection between the West and the non-West."
Looking for more multicultural fashion inspiration photos? Check out these:
Unknown cosplayer at Eurosteamcon Barcelona 2014