I studied graphic design, and as a novice artist, I can explain the choice in colors. In color theory, each colors represent different emotions. Let's just say that they exude different vibe. Green is mostly used as a sign that something is safe and healthy. Yellow is mostly used for cautions. Red is used to convey danger, dread, terror and horror. The same message used in traffic light, where green means safe, yellow means caution, and red means STAY AWAY OR DIE BRUH