UserGuiding lets you choose your own Launcher Image to make your onboarding material more like a native UI element on your application's interface.
This operation could be done while creating or editing a Checklist or a Help Center under:
Checklist Tab > Create a New Checklist or
Checklist Tab > Choose an Existing Checklist to edit
Here you will able to edit the launcher icon;
You can use a .jpeg or a .png file for the launcher image.
While applying an Image do not forget that it is going to be rounded. So try to apply inside paddings for the logo within the image.
On the example above let's suppose you are working on a 100px H / 100px W file.
Try to apply at least 20px of inside margins from all sides to make sure your logo will be displayed properly.