unless absolutely necessary...mucking about with the symbolic table--just to implement a shortcut to a programming problem--is generally not a great thing. in this particular case i think a closure would be a cleaner solution. even if you're just learning about symbolic table by using some code..it's better to have example code that uses the symbolic table for good reason, or you could get into a habit of using symbolic table in a similar fashion to the artificial example provided. anyway, that's my rant about symbolic tables in perl.
i like to read the ampersand in similar way to reading C, where it's literally "address of" operator. it's not exactly that in perl, but probably close enough for most purposes. so in that context the example line starting with ampersand would read: the address of an anonymous sub containing code/literal "color" is assigned the sub on the right hand side.
but as per my rant...it would be less error prone and clearer to have a sub that takes the color as a parameter, and do something with that. with subs/functions things are easily extended..you get into a fight with symbolic table manipulations if you (for example) add similar code for handling (say) transparency and visibility etc other parameters. the main program starts looking like spaghetti code.