There are some materials linked in these threads:
https://forum.inaturalist.org/t/does-anyone-have-inaturalist-poster-or-brochure-designs-to-share/2086
https://forum.inaturalist.org/t/how-to-use-inaturalist-postcards/4911
https://forum.inaturalist.org/t/presentations-about-inaturalist/9240
The press page also has some pngs you can play around with.