Company calendar is a shared calendar for all account users (company employees) that can be found under Calendar > Company Calendar:
To edit calendar parameters such as Color & Access Permissions use Edit option.
This section allows to set default calendar color (you can later customize each new event color as well, this color will set as default) & add users to configure access to the calendar:
By default, all Bitrix24 users (All visitors) can add & edit events in the Company Calendar. Account administrators can configure Access Permissions for the company calendar at any time. Use Add tab to add users and select access level for them.
To configure work time parameters (e.g. weekends and holidays which will be visually marked in the calendar) please go to Settings > Account Settings:
Company Calendar can also be found under each user's My Calendar section, so that users won't miss important events.