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