Look in org.gnome.shell.extensions.dash-to-dock with "dconf Editor", specifically the custom-theme-dot-border-color and custom-theme-running-dots-color both set to #e95420 (orange).
However, besides the dots it looks like we're stuck with orange in the window preview of the Dock (and also when alt-tabbing).
You can change the dot colours with dconf.
Look in org.gnome. shell.extension s.dash- to-dock with "dconf Editor", specifically the custom- theme-dot- border- color and custom- theme-running- dots-color both set to #e95420 (orange).
However, besides the dots it looks like we're stuck with orange in the window preview of the Dock (and also when alt-tabbing).
C.