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