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