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