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