In face-to-face communication, nonverbal behaviors such as facial expression, gaze, paralanguage and body movement are mutually synchronized between talkers. This synchrony of nonverbal behaviors creates a sense of unity in human communication and brings an activation among talkers as a congenial atmosphere. In constant, in online communication through videos, it is hard to create a congenial atmosphere, because nonverbal cues and pauses are difficult to understand during conversations. To address the lack of nonverbal clues in online communication, we have developed a communication system that expresses an activated atmosphere. The system enhanced a sense of unity by changing the background color from black to orange depending on the activation level. However, when a conversation starts to slow down, it was confirmed that changing to black gives a negative impression. Therefore, a new expression method is desired to ease silence without dark colors. In this study, we developed a hue expression method for visualization of congenial atmosphere. The developed method creates a relaxed conversational environment by softening the impression of silence due to changing hue.