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