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