You can ask directly Splunk if you can have the Media Kit (logos and images). Check the press corner and media kit pages. If you have an Account manager you can ask for some presentation kit (like the cheatsheats for Splunk).
Here you have the pdf of the quick ref: https://www.splunk.com/pdfs/solution-guides/splunk-quick-reference-guide.pdf
Hope it helps.
i contacted the web team and had them fix the link on https://www.splunk.com/en_us/newsroom/media-kit.html. It now takes you to https://www.splunk.com/en_us/newsroom/splunk-stock-photos.html which has logos and other resources.