The house colors were metallic gold (around #ffe3a4) and light red (around #e44033). This can typically be achieved using the Pale Red and Pale Brown dye module.
 
Wearing the house colors wasn't expected from all members at all times. Casual wear was common, and people had different clothing and armor for different tasks; however, when acting in an official capacity as a member of the house--ceremonies, meetings, etc.--the gold and red was generally expected, and typically considered a rebellious act to not have some prominent sign of membership.