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