There are numerous professional organizations and groups within large professional organizations that promote and support members of underrepresented groups. You can find these using a search engine such as Google or Bing by entering a profession, a minoritized group of people, and terms such as "organization" or "association." Look for a Membership link if you don't see a link for Students right away.
Here are a few examples:
MAPS was created to increase the pipeline of minorities into all health professions, inclusive of medicine, nursing, public health, health care administration and entrepreneurship.