Change highlight color in Mavericks preview?
I'm afraid this is not possbile anymore as Apple removed the workaround via the Fonts-Menu.

Discussed in the Apple Support Forum here : 
https://discussions.apple.com/thread/4145911?start=15&amp;tstart=0 
(same problem with underline colors) 
and on MacRumors here :
http://forums.macrumors.com/showthread.php?t=1658053 
where they discussed what has changed since ML.