You cannot change the default collector color.
But you can manipulate the views so that they look like this without slowing down the application.

I created this with 2 WKInterfaceGroupvertically aligned. The group on top has WKInterfaceLabelfor the custom label labels, and the group below has WKInterfacePicker. WKInterfacePickerconfigured as such:
Style: List
Focus Style: None
Indicator: Disabled
, .
WKInterfaceGroup . WKInterfaceGroup , .
pickerDidFocus pickerDidResignFocus, WKInterfaceGroup , WKInterfaceGroup .
picker action , .
, WKInterfacePicker, .