Blake did his Job illustrations in his sixties, near the end of a long and productive life. It contains in essence, but comprehensive and succinct, the same myth as do all the others. Job is the story of Albion, of Blake and his world, of you and me and ours. If you study nothing Blakean but Job, it will yield an accurate picture of Blake's system of thought, what he is about, and what he feels and believes most deeply.
Kathleen Raine, near the end of her life published a little book called Golgonoonza. It contains a very good treatment of Blake's Job. Beginning with Plate One Blake wrote this quote from II Corinthians 3:6: "the letter killeth but the spirit giveth life". We see a self-satisfied looking family with their musical instruments hanging from the tree, but not used. This family lives by the law.
And the law killed Job's children ("Our children are dead to us when we cease to love them and pass moral judgements upon them"; page 127). Job has not learned that the Spirit of God is 'the continual forgiveness of sins', which is to say that Job doesn't know God.
On page 127 she wrote, "It is clear that the figure of Albion is to a great extent derived from the Book of Job", although he didn't get around to dealing with it artistically until very late in his career.
There are many good presentations of Blake's Job on the web. The most helpful one might be in a work emanating from Boston College.
This one has a frame with the King James Version of the Bible pointed to by Blake in his magnificent production. Remarkably the text spread around Blake's pictures appear to have almost verbatim copies of various parts of the Bible Book of Job.
Here is the initial picture of another of the Job series. Click on the Next to see the successive pictures one by one. Blake's Job passed through all the joy and woe that inform peoples' lives; he was proud of his family (like the rich fool Jesus spoke of, he suffered like we all do from our arrogance and self-centeredness; he reached out for help in his misery, found God, and lived happily ever after. Here is the last picture. These pictures, like most of Blake's pictorial art are largely diagrammatic, designed to convey spiritual meaning.