PDF (portable document format) has been the standard file format for many years in the printing and signage industries.
PDF was designed especially for printing and sign-making to retain all the exact colours, fonts and other features in the file - so that you get exactly what you want when the file is printed.
As with most file formats there are various options and settings that can used - so ask your printer or sign-maker to tell you the best settings to use.
With photography and other colour-critical printing colour management is also important.