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