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