This study investigates the design of visual cues in rich notifications for mobile application user interfaces and the impact of different colors on users’ cognitive perceptions. The aim is to enhance users’ task performance and subjective evaluations, ensuring that users can quickly identify critical events and take timely actions. The experiment utilized smartphones as the test equipment to simulate rich notification user interfaces and user interactions. The study recorded participants’ operational behaviors and subjective perceptions of the visual cues in rich notifications. A total of 30 participants were recruited through convenience sampling. The study employed the System Usability Scale (SUS), a 7-point Likert scale subjective evaluation questionnaire, and semi-structured interviews to examine the effects of different visual cue colors on users. A one-way ANOVA was conducted to analyze the influence of different visual cue colors (red, yellow, and green) on users’ subjective perceptions. The results indicate that: (1) Red visual cues are suitable for conveying urgent states or high-risk critical signals, such as monitoring head areas for risks like obstruction of the mouth or nose. (2) Yellow visual cues are appropriate for indicating situations that require attention but are not urgent, such as monitoring specific body activities like rolling over. (3) Green visual cues are ideal for indicating normal states, such as monitoring general routine body activities, providing a sense of safety. (4) Graded visual cues, which use different colors based on the severity of the situation, allow the visual cues to more accurately reflect the status. The findings of this study provide important design recommendations for visual cues in rich notification user interfaces, enhancing the user experience and perception.