unDraw - Browse to find the images that fit your needs.

Undraw is most popular and one of the rare platforms where you will be directly thrown into the image collections without having to navigate here and there to finally get to the actual images you want.

The site is minimalistic, and you can pick a color for the images that suit your brand identity. There is not much to explain about this site. All you got to do is to just explore, and download.