Both of your sentences are grammatical, and they both seem to describe the same construction; but they don't mean quite the same thing.
... each element ... is shown separately and is attached ... Here you have a conjoined predicate—in effect, two predicates sharing the same subject:
is shown separately
each element and
is attached ...
... each element ... is shown separately attached ... Here you have a single predicate:
each element is shown separately attached ...
In this case, separately and attached cannot be taken as two distinct predicates: we parse separately as an adverb modifying attached.
Note in particular that attached ... cannot be taken as a 'reduced relative clause' = which is attached ... because a) there's no noun in the predicate which it can modify†, and b) in any case, there's no relative clause in your original to reduce.
JavaLatte's suggestion of a comma following separately presents an adequate solution:
... each element ... is shown separately, attached ...
The comma marks attached ... as a supplement outside the core structure of the main clause. It is parsed as an adjectival participle clause, and may be taken either as a 'gloss' on separately or as a second, subordinated predicate—in this case they amount to pretty much the same thing.
† In theory the main clause itself could be the 'fallback' referent, but that would be semantically nonsensical—you can't attach the act of showing to a syntactic category!