He was the kind of man you'd picture if you were painting your ideal.
Literal
Ideal [object-を] picture [in-に] drew [like-ような] man was.
理想を絵に描いたような is an idiom meaning 'picture-perfect, as if painted from an ideal' — used to describe someone or something that matches an ideal perfectly. The whole phrase modifies 男性 as a relative clause. Past tense だった ('was') adds a narrative or retrospective quality.