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