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