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