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