One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,8,6,3,4,7)(9,10,14,19,15,20,13,18)(11,21,24,32,25,31,23,16)(12,26,27,17,29,33,28,34)(22,36,37,35,39,30,38,40)(9,11,13,23,15,25,14,24)(10,16,19,21,20,32,18,31)(12,22,27,37,29,39,28,38)(17,30,26,35,34,36,33,40)(1,3)(2,6)(4,8)(5,7)(9,12)(10,17)(11,22)(13,27)(14,28)(15,29)(16,30)(18,33)(19,26)(20,34)(21,35)(23,37)(24,38)(25,39)(31,40)(32,36) involution — undirected(1,4,6,5)(2,7,3,8)(9,13,15,14)(10,18,20,19)(11,23,25,24)(12,27,29,28)(16,31,32,21)(17,33,34,26)(22,37,39,38)(30,40,36,35)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.