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