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