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