In Google Forms click Send, choose the link icon and tick "Shorten URL". The forms.gle link is short, which gives you a small, clean code; the full docs.google.com link makes a dense one. Paste the short link above.
Forms are scanned in classrooms, at events and on the back of a receipt. A frame line that names the reward ("30 seconds, helps us a lot") does more than any colour. For a classroom projector, use the PNG export at 2048 px and show it full screen.
Questions
Does the form open in the app or the browser?
In the browser, where Google Forms works fully on mobile. Respondents do not need a Google account unless you require one in the form settings.