It is currently unclear what the industry standard for consent UI would be. However, Google has shared its guidance at Cookiechoices.org
The first pop-up of this reference design gives a general disclosure and asks for users consent. The user can click on the link and get more details, including the full list of all partners who might have access to data.
If the user agrees, personalised ads can be served.
If the user declines, the second window is shown, informing that the ads will still be on the site, but they will not be personalised. This warning language also states that cookies will still be used on the site. This is similar to the old "cookie notification" banner, which does not require opt-in consent.
Clickio has developed a simple GDPR Consent Tool
for publishers based on this reference design. It is currently live and available free of charge for all our publishers.