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