One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,7,6,3,4,8)(9,10)(11,21)(12,26,29,34)(13,18)(14,19)(15,20)(16,24)(17,27,33,28)(22,36,38,30)(23,32)(25,31)(35,37,40,39)(1,3,6,2)(4,8,5,7)(9,11,13,24,15,25,14,23)(10,16,19,21,20,32,18,31)(12,22,27,39,29,38,28,37)(17,30,34,35,33,36,26,40)(9,12)(10,17)(11,22)(13,27)(14,28)(15,29)(16,30)(18,26)(19,34)(20,33)(21,35)(23,37)(24,39)(25,38)(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)(16,21,32,31)(17,26,33,34)(22,37,38,39)(30,35,36,40)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.