Richly malty is right. I would have expected disgustingly cloying but it must work or no-one would want to drink it.
@Margowicz, I don't know what you mean by "guide". There are explanations of Lovibond (L) and European Beer Colour (EBC) on Wikipedia if you want to read about them. There are loads of converters from one to the other,Clibit gave you a link to one.
You might have a problem sourcing exactly the crystal malt that recipe specifies, American maltsters tend to do things differently to UK maltsters, they have a range of crystal malts of different darkness, UK maltsters only have 3 or 4. You might have to use "light, medium, and dark crystal" but that won't make exactly that recipe. You might be in America of course, in which case disregard what I typed. Do you use any brewing software? That might help you get the right combination to get the right right colour at least, might be tedious to do, mind.