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