No, you can't do that in the current version.
This was a feature request that languished a while (since 2003): Events spanning days are seen as multiple events (display), and was then watered down into this: Add markers for multi-day events in multiday views
The watered-down requirement was to have made the 0.9 release according to the Sunbird 0.9 release notes,
* Events spanning days now have a visual indicator indicating them as connected events
* When reloading a remote calendar a progress indicator is now shown
* The so-called "minimonth" (small calendar month in the upper left) has been given a visual overhaul
* The calendar views (day, week, multiweek, month) have been given a visual overhaul
* CalDAV support and interoperability with various CalDAV servers has been improved
* The application stability and memory consumption has been greatly improved
* A full list of changes that have gone into this release can be found on The Rumbling Edge website
but I don't see the visual indicators either on the Sunbird 0.9 version on Ubuntu.
It is in the Sunbird UI mockups so it definitely is on their radar. Going by past history alone, I wouldn't expect to see this feature anytime soon.