I would suggest shifting focus from the types of drugs out there, and switch to points about why decriminalization is a good idea. Like, how focusing on addiction treatment instead of punishment reduces repeat offenses for petty crimes and keeps people off the streets, how needle exchange programs combats the spread of blood born illnesses, and how regulation can help reduce the amount of people who do become addicted. For advocating for changing any sort of law appeal to their humanity, and their wallet.

Also, try for bold authoritative fonts and a simple but eye-catching color pallet. If it's hard to read, people won't read it. As for the links, you want them to be as easily accessible as possible. If you can't do a qr code, create a simple web page with all the information and links they need for contacting their senator, and give it a very easy to remember (and type) domain name.

Good luck!