Emotional awareness and reflection through self-tracking can enhance mental well-being, and personal informatics systems facilitate this practice through diverse methods of expression. However, existing tools offer limited opportunities for meaning-based personalization combined with adaptive support. We developed Hueman, a color-forward emotion tracking and management system that learns from each user’s unique color-emotion associations and uses them to adapt mobile color themes for emotional adjustment. Through a preliminary evaluation with seven participants, we found that Hueman prompted reflection on existing color-emotion associations and ways that color shapes everyday emotional experiences. We observed that the impact of color-based user interface themes varied according to individual experiences, personal associations, and situational context. These findings highlight the potential of color as an expressive medium and suggest ways mobile devices can be intentionally used for emotional support.