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