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