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