Never opposed to diversity, but I don't really think the issue you bring up comes from the product. If there an issue, I think it would stem from the community. Don't be dicks can be a tall order. If you harbor an accepting community, I think that does the trick.

Introduce yourself to anyone who walks in the store and is curious about the hobby. That's how you make the hobby inviting to a more diverse audience Imo. But ya, there can be some minor diversity in products for instance the celestial lions chapter. Or here is an image from the genestealer cult battle force box for the holiday. https://www.games-workshop.com/resources/catalog/product/920x950/99120117006_GenestealerCultsNeophyteHybridSquad01.jpg