The below is my initial line sketch of St James in praise and part of a group of apostles. Here's a blog from 2014 about St James and the Spanish "way", a traditional pilgrimage route.
The Life of St James and his Appearance
Western artists have shown St James as a more youthful apostle although he might be portrayed with gray or white hair like in the apse at St. Paul Outside the Walls, for example below. I haven’t researched this more. Perhaps it was to signify that he is an official "elder of the church" and wise, for which white or gray hair would be an symbolic attribute:
A gray head is a crown of glory; It is found in the way of righteousness.
The glory of young men is their strength, And the honor of old men is their gray hair.
As an apostle, he might bear a scroll or bible.
You might see St James with a scallop shell, staff and gourd or flask because he is associated with pilgrimages. He is not to be confused with St Roch who is often portrayed similarly, except that St Roch, who survived a bout of plague, exhibits his healed leg.
The patrimony of St James
St James is an example of promptness and generous adherence to Christ. He was the first to drink the Chalice of Christ's passion as a martyr. "In following Jesus, like St James, we know that even in difficulties we are on the right path." Pope Emeritus Benedict XVI in Apostles p. 68
O gracious God, we remember before thee this day thy servant and apostle James, first among the Twelve to suffer martyrdom for the Name of Jesus Christ; and we pray that thou wilt pour out upon the leaders of thy Church that spirit of self-denying service by which alone they may have true authority among thy people; through the same Jesus Christ our Lord, who liveth and reigneth with thee and the Holy Spirit, one God, now and for ever.