Per §25-1-131 C.R.S., the Colorado Department of Public Health and Environment is making information publicly available regarding the legal requirements for firearms safe storage in Colorado on its website:
Colorado state law requires that firearms be responsibly and securely stored when they are not in use to prevent access by unsupervised juveniles and other unauthorized users (§18-12-114 C.R.S.). Unlawful storage of a firearm is a class 2 misdemeanor.
Unlawfully providing a handgun to a juvenile or permitting a juvenile to possess a handgun is a class 4 felony (§18-12-108.7(1)(b) C.R.S.). Unlawfully providing a firearm other than a handgun to a juvenile is a class 1 misdemeanor (§18-12-108.7(3) C.R.S.).
Additionally, licensed firearm retailers are required to post a notice of this requirement and provide locking mechanisms with each firearm transfer (§18-12-405 C.R.S.). Violation is a class 2 misdemeanor with penalties of imprisonment or fine up to $500.