How about:
@startuml
partition Conductor {
"Climbs on Platform" --> === S1 ===
--> Bows
}
(*) --> "Climbs on Platform"
partition Audience #LightSkyBlue {
=== S1 === --> Applauds
}
partition Conductor {
Bows --> === S2 ===
--> WavesArmes
Applauds --> === S2 ===
}
partition Orchestra #CCCCEE {
WavesArmes --> Introduction
--> "Play music"
}
@enduml
There was as subsequent question in the comment how about:
@startuml
partition Orchestra {
play -[hidden]-> play
}
(*) --> play
play --> end
@enduml